Publications by authors named "Arun Pal"

40 Publications

Concomitant gain and loss of function pathomechanisms in C9ORF72 amyotrophic lateral sclerosis.

Life Sci Alliance 2021 04 22;4(4). Epub 2021 Feb 22.

Translational Neurodegeneration Section "Albrecht-Kossel," Department of Neurology, and Center for Transdisciplinary Neuroscience (CTNR), University Medical Center Rostock, University of Rostock, Rostock, Germany

Intronic hexanucleotide repeat expansions (HREs) in are the most frequent genetic cause of amyotrophic lateral sclerosis, a devastating, incurable motoneuron (MN) disease. The mechanism by which HREs trigger pathogenesis remains elusive. The discovery of repeat-associated non-ATG (RAN) translation of dipeptide repeat proteins (DPRs) from HREs along with reduced exonic C9ORF72 expression suggests gain of toxic functions (GOFs) through DPRs versus loss of C9ORF72 functions (LOFs). Through multiparametric high-content (HC) live profiling in spinal MNs from induced pluripotent stem cells and comparison to mutant FUS and TDP43, we show that HRE caused a distinct, later spatiotemporal appearance of mainly proximal axonal organelle motility deficits concomitant to augmented DNA double-strand breaks (DSBs), RNA foci, DPRs, and apoptosis. We show that both GOFs and LOFs were necessary to yield the overall pathology. Increased RNA foci and DPRs concurred with onset of axon trafficking defects, DSBs, and cell death, although DSB induction itself did not phenocopy C9ORF72 mutants. Interestingly, the majority of LOF-specific DEGs were shared with HRE-mediated GOF DEGs. Finally, C9ORF72 LOF was sufficient-albeit to a smaller extent-to induce premature distal axonal trafficking deficits and increased DSBs.
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http://dx.doi.org/10.26508/lsa.202000764DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7918691PMC
April 2021

Polymorphism Dependent 9-Phosphoanthracene Derivative Exhibiting Thermally Activated Delayed Fluorescence: A Computational Investigation.

J Phys Chem A 2020 Dec 17;124(52):11025-11037. Epub 2020 Dec 17.

School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, WB, India.

Polymorphs of anthracene derivatives exhibit diverse photophysical properties that can help to develop efficient organic-based photovoltaic devices. 10-Anthryl-9-phosphoanthracene (10-APA) shows different photophysical behaviors for the solid state due to its variety in crystalline arrangement. Herein, we investigate the ground and excited-state properties of the monomer and two different polymorphs of 10-APA from . Calculations reveal that strong spin-orbit coupling (SOC) between first excited singlet state (S) and triplet manifolds at their S-optimized geometries enabling the reverse intersystem crossing (RISC). The electron-vibration coupling (Huang-Rhys factor) in the excited state is the most relevant factor here. For both ISC and RISC, a similarity in Huang-Rhys factors for the molecular vibration along the π···π stacking at low-frequency region makes the rates effective. On the other side, the nonvanishing vibronic relaxation modes provide a relatively slower RISC rate in the red crystal. However, for the red crystal, small reorganization energy (λ) and large Huang-Rhys factor toward S → S conversion reduce nonradiative decay, leading to a prompt fluorescence. As the feasibility of S ↔ T conversion increases in the yellow dimer, it allows a delay in fluorescence emission, leading to thermally activated delayed fluorescence (TADF).
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http://dx.doi.org/10.1021/acs.jpca.0c10203DOI Listing
December 2020

Paradoxical design of a serendipitous pyrazolate bridging mode: a pragmatic strategy for inducing ineluctable ferromagnetic coupling.

Dalton Trans 2020 Oct;49(39):13704-13716

School of Chemical Sciences, Indian Association for the Cultivation of Science, Raja S. C. Mullick Road, Kolkata 700032, India.

In this contribution we have carried out a systematic magnetostructural investigation to establish a robust one-to-one correlation between the quasi-orthogonal bridging mode of a pyrazolate ring and ferromagnetic coupling. Generating a complex with an elusive quasi-orthogonal pyrazolate bridging is a challenging task but would ineluctably result in a ferromagnetic exchange pathway. Notwithstanding the rarity, we report herein a series of bis-pyrazolato copper complexes. We have successfully exploited a so-called hypothetical-deductive model on a particular set of ligand systems that forced the pyrazolate moiety to adopt an unusual bridging mode with the M-Npz-Npz-M torsion angles in the range from 49.7° to 72.8°. The corroborating variable temperature direct current (DC) magnetic susceptibility data unequivocally confirm the ferromagnetic coupling for the complexes with the torsion angles greater than 71.37°. Furthermore, the experimental results are in excellent agreement with theoretical calculations. Based on density functional theory (DFT) calculations, again a one-to-one correspondence is made between the ligand structure and magnetic behaviour. The diradical character (y0) of the complexes is correlated with the extent of bonding interactions between the Cu centers and hence, their ferromagnetic or antiferromagnetic nature. The broken symmetry (BS) calculations on the magnetically active molecular orbitals indicate the essential magnetic behaviour of the complexes, while the EPR g-tensor calculations confirm that dx2-y2 is the magnetic orbital.
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http://dx.doi.org/10.1039/d0dt02468fDOI Listing
October 2020

Immobilization of a Polar Sulfone Moiety onto the Pore Surface of a Humid-Stable MOF for Highly Efficient CO Separation under Dry and Wet Environments through Direct CO-Sulfone Interactions.

ACS Appl Mater Interfaces 2020 Sep 1;12(37):41177-41184. Epub 2020 Sep 1.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.

The stability of microporous metal-organic frameworks (MOFs) in moist environments must be taken into consideration for their practical implementations, which has been largely ignored thus far. Herein, we synthesized a new moisture-stable Zn-MOF, , , by utilizing a bent organic linker 4,4'-sulfonyldibenzoic acid (HSDB) containing a polar sulfone group (-SO) and a N, N-donor spacer () with a Brunauer-Emmett-Teller surface area of 216 m g. This material displays greater CO adsorption capacity over N and CH with high IAST selectivity, which is also validated by breakthrough experiments with longer breakthrough times for CO. Most importantly, the separation performance is largely unaffected in the presence of moisture of simulated flue gas stream. Temperature-programmed desorption (TPD) analysis shows the ease of the regeneration process, and the performance was verified for multiple cycles. In order to understand the structure-function relationship at the atomistic level, grand canonical Monte Carlo (GCMC) calculation was performed, indicating that the primary binding site for CO is between the sulfone moieties in . CO is attracted to the bonded structure (V-shape) of the sulfone moieties in a perpendicular fashion, where C is aligned with S, and the CO axis bisects the SO axis. Thus, the strategic approach to immobilize the polar sulfone moiety with a high number of inherent stronger M-N coordination and the absence of coordination unsaturation made this MOF potential toward practical CO separation applications.
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http://dx.doi.org/10.1021/acsami.0c07380DOI Listing
September 2020

A "Thermodynamically Stable" 2D Nickel Metal-Organic Framework over a Wide pH Range with Scalable Preparation for Efficient C s over C Hydrocarbon Separations.

Chemistry 2020 Oct 11;26(55):12624-12631. Epub 2020 Sep 11.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, 721302, WB, India.

The design and construction of "thermodynamically stable" metal-organic frameworks (MOFs) that can survive in liquid water, boiling water, and acidic/basic solutions over a wide pH range is highly desirable for many practical applications, especially adsorption-based gas separations with obvious scalable preparations. Herein, a new thermodynamically stable Ni MOF, {[Ni(L)(1,4-NDC)(H O) ]} (IITKGP-20; L=4,4'-azobispyridine; 1,4-NDC=1,4-naphthalene dicarboxylic acid; IITKGP stands for the Indian Institute of Technology Kharagpur), has been designed that displays moderate porosity with a BET surface area of 218 m  g and micropores along the [10-1] direction. As an alternative to a cost-intensive, cryogenic, high-pressure distillation process for the separation of hydrocarbons, MOFs have recently shown promise for such separations. Thus, towards an application standpoint, this MOF exhibits a higher uptake of C hydrocarbons over that of C hydrocarbon under ambient conditions, with one of the highest selectivities based on the ideal adsorbed solution theory (IAST) method. A combination of two strategies (the presence of stronger metal-N coordination of the spacer and the hydrophobicity of the aromatic moiety of the organic ligand) possibly makes the framework highly robust, even stable in boiling water and over a wide range of pH 2-10, and represents the first example of a thermodynamically stable MOF displaying a 2D structural network. Moreover, this material is easily scalable by heating the reaction mixture at reflux overnight. Because such separations are performed in the presence of water vapor and acidic gases, there is a great need to explore thermodynamically stable MOFs that retain not only structural integrity, but also the porosity of the frameworks.
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http://dx.doi.org/10.1002/chem.202001611DOI Listing
October 2020

Two Closely Related Zn(II)-MOFs for Their Large Difference in CO Uptake Capacities and Selective CO Sorption.

Inorg Chem 2020 May 28;59(10):7056-7066. Epub 2020 Apr 28.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, WB, India.

Two azo functionalized Zn(II)-based MOFs, {[Zn(SDB)(3,3'-L)]·G}, IITKGP-13A, and {[Zn(SDB)(4,4'-L)]·G}, IITKGP-13B (IITKGP stands for Indian Institute of Technology Kharagpur), have been constructed through the self-assembly of isomeric N,N'-donor spacers (3,3'-L = 3,3'-azobispyridine and 4,4'-L = 4,4'-azobispyridine) with organic ligand 4,4'-sulfonyldibenzoic acid (SDBH) and Zn(NO)·6HO (G represents disordered solvent molecules). Single-crystal X-ray diffraction studies reveal the 2D structure with topology for both MOFs. However, the subtle change in positions of coordinating N atoms of spacers makes IITKGP-13A noninterpenetrated, while IITKGP-13B bears a 2-fold interpenetrated structure. IITKGP-13A exhibits higher uptake of CO over CH and N with high IAST selectivities for mixed CO/CH (50:50, biogas) and CO/N (15:85, flue gas) gas systems. In contrast, IITKGP-13B takes up very low amount of CO gas (0.4 mmol g) compared to IITKGP-13A (1.65 mmol g) at 295 K. Density functional theory (DFT)-based electronic structure calculations have been performed to explain the origin of the large differences in CO uptake capacity between the two MOFs at the atomistic level. The results show that the value of the change in enthalpy (Δ) at 298 K temperature and 1 bar pressure for the CO adsorption is more negative in IITKGP-13A as compared to that in IITKGP-13B, thus indicating that CO molecules are more favored to get adsorbed in IITKGP-13A than in IITKGP-13B. The computed values for the Gibbs' free energy change (Δ) for the CO adsorption are positive for both of the MOFs, but a higher value is observed for the IITKGP-13B. The noncovalent types of interactions are the main contribution toward the attractive energies between the host MOF frameworks and guest CO molecules, which has been studied with the help of energy decomposition analysis (EDA).
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http://dx.doi.org/10.1021/acs.inorgchem.0c00551DOI Listing
May 2020

Combined Dendritic and Axonal Deterioration Are Responsible for Motoneuronopathy in Patient-Derived Neuronal Cell Models of Chorea-Acanthocytosis.

Int J Mol Sci 2020 Mar 5;21(5). Epub 2020 Mar 5.

Section for Translational Neurodegeneration "Albrecht Kossel", Department of Neurology, Universitätsmedizin Rostock, 18057 Rostock, Germany.

Chorea acanthocytosis (ChAc), an ultra-rare devastating neurodegenerative disease, is caused by mutations in the gene, which encodes for the protein chorein. Affected patients suffer from chorea, orofacial dyskinesia, epilepsy, parkinsonism as well as peripheral neuropathy. Although medium spinal neurons of the striatum are mainly affected, other regions are impaired as well over the course of the disease. Animal studies as well as studies on human erythrocytes suggest Lynkinase inhibition as valuable novel opportunity to treat ChAc. In order to investigate the peripheral neuropathy aspect, we analyzed induced pluripotent stem cell derived midbrain/hindbrain cell cultures from ChAc patients in vitro. We observed dendritic microtubule fragmentation. Furthermore, by using in vitro live cell imaging, we found a reduction in the number of lysosomes and mitochondria, shortened mitochondria, an increase in retrograde transport and hyperpolarization as measured with the fluorescent probe JC-1. Deep phenotyping pointed towards a proximal axonal deterioration as the primary axonal disease phenotype. Interestingly, pharmacological interventions, which proved to be successful in different models of ChAc, were ineffective in treating the observed axonal phenotypes. Our data suggests that treatment of this multifaceted disease might be cell type and/or neuronal subtype specific, and thus necessitates precision medicine in this ultra-rare disease.
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http://dx.doi.org/10.3390/ijms21051797DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084777PMC
March 2020

Transition-State-like Planar Structures for Amine Inversion with Ultralong C-C Bonds in Diamino--carborane and Diamino--dodecahedron.

J Am Chem Soc 2020 03 4;142(11):5331-5337. Epub 2020 Mar 4.

School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, 700032 Kolkata, West Bengal, India.

Umbrella-like inversion of pyramidalized amines proceed through a planar transition state (TS). Stabilization of the TS through N(lone-pair) → σ*(C-C) "negative hyperconjugation" in diamino--carborane () causes rapid inversion in the amine, which results in the observation of a planarized -NH from the X-ray crystal structure. This proceeds through quantum mechanical tunneling across the small and narrow barrier (low pyramidalization). Tuning this secondary orbital (donor-acceptor) interaction for various derivatives of and diamino--dodecahedron () provides a rational approach toward increasing to as large as 2.001, 2.011, and 1.807 Å for (amino oxide--carborane), (di--dimethylamino--carborane), and (di--diisopropylamino-o-dodecahedron), respectively.
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http://dx.doi.org/10.1021/jacs.0c00181DOI Listing
March 2020

Knocking out C9ORF72 Exacerbates Axonal Trafficking Defects Associated with Hexanucleotide Repeat Expansion and Reduces Levels of Heat Shock Proteins.

Stem Cell Reports 2020 03 20;14(3):390-405. Epub 2020 Feb 20.

Technische Universität Dresden, Center for Regenerative Therapies TU Dresden (CRTD), 01307 Dresden, Germany. Electronic address:

In amyotrophic lateral sclerosis (ALS) motor neurons (MNs) undergo dying-back, where the distal axon degenerates before the soma. The hexanucleotide repeat expansion (HRE) in C9ORF72 is the most common genetic cause of ALS, but the mechanism of pathogenesis is largely unknown with both gain- and loss-of-function mechanisms being proposed. To better understand C9ORF72-ALS pathogenesis, we generated isogenic induced pluripotent stem cells. MNs with HRE in C9ORF72 showed decreased axonal trafficking compared with gene corrected MNs. However, knocking out C9ORF72 did not recapitulate these changes in MNs from healthy controls, suggesting a gain-of-function mechanism. In contrast, knocking out C9ORF72 in MNs with HRE exacerbated axonal trafficking defects and increased apoptosis as well as decreased levels of HSP70 and HSP40, and inhibition of HSPs exacerbated ALS phenotypes in MNs with HRE. Therefore, we propose that the HRE in C9ORF72 induces ALS pathogenesis via a combination of gain- and loss-of-function mechanisms.
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http://dx.doi.org/10.1016/j.stemcr.2020.01.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7066330PMC
March 2020

A Phosphate-Based Silver-Bipyridine 1D Coordination Polymer with Crystallized Phosphoric Acid as Superprotonic Conductor.

Chemistry 2020 Apr 19;26(20):4607-4612. Epub 2020 Mar 19.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302, India.

Phosphate-based silver-bipyridine (Ag-bpy) 1D coordination polymer {[{Ag(4,4'-bpy)} {Ag(4,4'-bpy)(H PO )}]⋅2 H PO ⋅H PO ⋅5 H O} (1) with free phosphoric acid (H PO ), its conjugate base (H PO ) and water molecules in its lattice was synthesized by room-temperature crystallization and the hydrothermal method. An XRD study showed that coordinated H PO , lattice H PO anions, free H PO and lattice water molecules are interconnected by H-bonding interactions, forming an infinitely extended 2D H-bonded network that facilitates proton transfer. This material exhibits a high proton conductivity of 3.3×10  S cm at 80 °C and 95 % relative humidity (RH). Furthermore, synthesis of this material from commercially available starting materials in water can be easily scaled up, and it is highly stable under extreme conditions of conductivity measurements. This report inaugurates the usage and design principle of proton-conducting frameworks based on crystallized phosphoric acid and phosphate.
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http://dx.doi.org/10.1002/chem.201905650DOI Listing
April 2020

Depending on the stress, histone deacetylase inhibitors act as heat shock protein co-inducers in motor neurons and potentiate arimoclomol, exerting neuroprotection through multiple mechanisms in ALS models.

Cell Stress Chaperones 2020 01 3;25(1):173-191. Epub 2020 Jan 3.

Department of Neurology and Neurosurgery and Montreal Neurological Institute, McGill University, 3801 University St., Montreal, QC, H3A 2B4, Canada.

Upregulation of heat shock proteins (HSPs) is an approach to treatment of neurodegenerative disorders with impaired proteostasis. Many neurons, including motor neurons affected in amyotrophic lateral sclerosis (ALS), are relatively resistant to stress-induced upregulation of HSPs. This study demonstrated that histone deacetylase (HDAC) inhibitors enable the heat shock response in cultured spinal motor neurons, in a stress-dependent manner, and can improve the efficacy of HSP-inducing drugs in murine spinal cord cultures subjected to thermal or proteotoxic stress. The effect of particular HDAC inhibitors differed with the stress paradigm. The HDAC6 (class IIb) inhibitor, tubastatin A, acted as a co-inducer of Hsp70 (HSPA1A) expression with heat shock, but not with proteotoxic stress induced by expression of mutant SOD1 linked to familial ALS. Certain HDAC class I inhibitors (the pan inhibitor, SAHA, or the HDAC1/3 inhibitor, RGFP109) were HSP co-inducers comparable to the hydroxyamine arimoclomol in response to proteotoxic stress, but not thermal stress. Regardless, stress-induced Hsp70 expression could be enhanced by combining an HDAC inhibitor with either arimoclomol or with an HSP90 inhibitor that constitutively induced HSPs. HDAC inhibition failed to induce Hsp70 in motor neurons expressing ALS-linked mutant FUS, in which the heat shock response was suppressed; yet SAHA, RGFP109, and arimoclomol did reduce loss of nuclear FUS, a disease hallmark, and HDAC inhibition rescued the DNA repair response in iPSC-derived motor neurons carrying the FUSmutation, pointing to multiple mechanisms of neuroprotection by both HDAC inhibiting drugs and arimoclomol.
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http://dx.doi.org/10.1007/s12192-019-01064-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985055PMC
January 2020

Remote Functionalization through Symmetric or Asymmetric Substitutions Control the Pathway of Intermolecular Singlet Fission.

J Chem Theory Comput 2019 Sep 26;15(9):5014-5023. Epub 2019 Aug 26.

School of Chemical Sciences , Indian Association for the Cultivation of Science , 2A & 2B Raja S. C. Mullick Road, Jadavpur , Kolkata 700032 , WB India.

Singlet fission (SF) produces two coupled triplet excitons from a high energy singlet excitation. The mechanism of SF in a variety of phenyl (-Ph) substituted pentacene is systematically studied through both and density functional theory calculations. Two classes of substitution to pentacene are considered, namely, symmetric configuration with four Ph groups (TPP) and an asymmetric configuration with two Ph groups (DPP). The positions of the singlet and triplet states are determined by calibrating the active space through state averaged complete active space self-consistent field (SA-CASSCF) calculations. The SF rates are computed based on restricted active space with single and double spin flip wave functions (RAS-SF and RAS-2SF), which are analyzed based on different intermolecular π-stacking patterns of TPP and DPP. The contribution of charge transfer (CT) state near the multiexciton (ME) state plays a significant role for SF efficiency. The role of excimer formation is supportive for ME generation [, , 617], and hence it is critically studied. The ME generation in TPP is a slower process and occurs through an excimer-mediated path with a large coupling between the first singlet excited state and ME state. On the other hand, DPP exhibits a relatively faster SF rate through the formation of a ME state via low-lying CT state, especially the slip-stacked dimers. The present computation elegantly demonstrates the crucial role of functional group substitution in the structure of SF active molecules in determining the efficiency of fission dynamics.
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http://dx.doi.org/10.1021/acs.jctc.9b00419DOI Listing
September 2019

A Microporous Co-MOF for Highly Selective CO Sorption in High Loadings Involving Aryl C-H···O═C═O Interactions: Combined Simulation and Breakthrough Studies.

Inorg Chem 2019 Sep 9;58(17):11553-11560. Epub 2019 Aug 9.

Department of Chemistry , Indian Institute of Technology Kharagpur , Kharagpur - 721302 , WB , India.

In the context of porous crystalline materials toward CO separation and capture, a new 2-fold interpenetrated 3D microporous Co-MOF, IITKGP-11 (IITKGP denotes Indian Institute of Technology Kharagpur), has been synthesized consisting of a 1D channel of ∼3.6 × 5.0 Å along the [101] direction with a cavity volume of 35.20%. This microporous framework with a BET surface area of 253 mg shows higher uptake of CO (under 1 bar, 3.35 and 2.70 mmol g at 273 and 295 K, respectively), with high separation selectivities for CO/N and CO/CH gas mixtures under ambient conditions as estimated through IAST calculation. Moreover, real time dynamic breakthrough studies reveal the high adsorption selectivity toward CO for these binary mixed gases at 295 K and 1 bar. Besides high gas separation selectivity, capacity considerations in mixed gas phases are also important to check the performance of a given adsorbent. CO loading amounts in mixed gas phases are quite high as predicted through IAST calculation and experimentally determined from dynamic breakthrough studies. In order to get insight into the phenomena, GCMC simulation was performed demonstrating that the CO molecules are electrostatically trapped via interactions between oxygen on CO and hydrogen on pyridyl moieties of the spacers.
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http://dx.doi.org/10.1021/acs.inorgchem.9b01402DOI Listing
September 2019

Three Co(II) Metal-Organic Frameworks with Diverse Architectures for Selective Gas Sorption and Magnetic Studies.

Inorg Chem 2019 May 18;58(9):6246-6256. Epub 2019 Apr 18.

Department of Chemistry , Indian Institute of Technology Kharagpur , Kharagpur-721302 , WB , India.

Three Co(II) metal-organic frameworks, namely, {[Co(L)(OBA)(HO)]· xG} (1), {[Co(L)(OBA)]· xG} (2), and {[Co(L)(OBA)(HO)]·DMA· xG} (3) [where L = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene, HOBA = 4,4'-oxybisbenzoic acid, DMF = dimethylformamide, DMA = dimethylacetamide, and G denotes disordered guest molecules], have been synthesized under diverse reaction conditions through self-assembly of a bent dicarboxylate and a linear spacer with a Co(II) ion. While 1 is crystallized at room temperature in DMF to form a 2D layer structure, 2 is formed by the assembly of similar components under solvothermal conditions with a 3D network structure. On the other hand, changing the solvent to DMA, 3 could be crystallized at room temperature with a 3D architecture. Out of the three, activated sample 2 was found to be permanently microporous in nature, with a BET surface area of 385 m/g, and exhibited moderately high uptake capacity for CH and CO while taking up much less CH and N at ambient conditions. As a result, high ideal adsorbed solution theory (IAST) separation selectivities are obtained for CO/N (15:85), CO/CH (50:50), and CH/CH (50:50) gas mixtures, making 2 a potential candidate for those important gas separations at ambient conditions. Moreover, the magnetic properties of 1-3 were studied. 1 and 2 show antiferromagnetic interaction between the Co(II) centers, whereas 3 displays ferromagnetic behavior arising from a counter-complementary effect between two types of links among Co(II) centers in 3.
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http://dx.doi.org/10.1021/acs.inorgchem.9b00471DOI Listing
May 2019

Metal-Organic Frameworks and Other Crystalline Materials for Ultrahigh Superprotonic Conductivities of 10  S cm or Higher.

Chemistry 2019 May 25;25(25):6259-6269. Epub 2019 Feb 25.

Department of Chemistry, Indian Institute of Technology Kharagpur, WB, 721302, India.

Proton-conducting materials in the solid state have received immense attention for their role as electrolytes in proton-exchange membrane fuel cells. Recently, crystalline materials-metal-organic frameworks (MOFs), hydrogen-bonded organic frameworks (HOFs), covalent organic frameworks (COFs), polyoxometalates (POMs), and porous organic crystals-have become an exciting research topic in the field of proton-conducting materials. For a better electrolyte, a high proton conductivity on the order of 10  S cm or higher is preferred as efficient proton transport between the electrodes is ultimately necessary. With an emphasis on design principles, this Concept will focus on MOFs and other crystalline solid-based proton-conducting platforms that exhibit "ultrahigh superprotonic" conductivities with values in excess of 10  S cm . While only a handful of MOFs exhibit such an ultrahigh conductivity, this quality in other systems is even rarer. In addition to interpreting the structural-functional correlation by taking advantage of their crystalline nature, we address the challenges and promising directions for future research.
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http://dx.doi.org/10.1002/chem.201806126DOI Listing
May 2019

Metalo Hydrogen-Bonded Organic Frameworks (MHOFs) as New Class of Crystalline Materials for Protonic Conduction.

Chemistry 2019 Feb 2;25(7):1691-1695. Epub 2019 Jan 2.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.

Recently, proton conduction has been a thread of high potential owing to its wide applications in fuel-cell technology. In the search for a new class of crystalline materials for protonic conductors, three metalo hydrogen-bonded organic frameworks (MHOFs) based on [Ni(Imdz) ] and arene disulfonates (MHOF1 and MHOF2) or dicarboxylate (MHOF3) have been reported (Imdz=imidazole). The presence of an ionic backbone with charge-assisted H-bonds, coupled with amphiprotic imidazoles made these MHOFs protonic conductors, exhibiting conduction values of 0.75×10 , 3.5×10 and 0.97×10  S cm , respectively, at 80 °C and 98 % relative humidity, which are comparable to other crystalline metal-organic framework, coordination polymer, polyoxometalate, covalent organic framework, and hydrogen-bonded organic framework materials. This report initiates the usage of MHOF materials as a new class of solid-state proton conductors.
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http://dx.doi.org/10.1002/chem.201805177DOI Listing
February 2019

High content organelle trafficking enables disease state profiling as powerful tool for disease modelling.

Sci Data 2018 11 13;5:180241. Epub 2018 Nov 13.

Division of Neurodegenerative Diseases, Department of Neurology, Technische Universität Dresden, Dresden, Germany.

Neurodegenerative diseases pose a complex field with various neuronal subtypes and distinct differentially affected intra-neuronal compartments. Modelling of neurodegeneration requires faithful in vitro separation of axons and dendrites, their distal and proximal compartments as well as organelle tracking with defined retrograde versus anterograde directionality. We use microfluidic chambers to achieve compartmentalization and established high throughput live organelle imaging at standardized distal and proximal axonal readout sites in iPSC-derived spinal motor neuron cultures from human amyotrophic lateral sclerosis patients to study trafficking phenotypes of potential disease relevance. Our semi-automated pipeline of organelle tracking with FIJI and KNIME yields quantitative, multiparametric high content phenotypic signatures of organelle morphology and their trafficking in axons. We provide here the resultant large datasets to enable systemic signature interrogations for comprehensive and predictive disease modelling, mechanistic dissection and secondary hit validation (e.g. drug screens, genetic screens). Due to the nearly complete coverage of analysed motility events, our quantitative method yields a bias-free statistical power superior over common analyses of a handful of manual kymographs.
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http://dx.doi.org/10.1038/sdata.2018.241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6233479PMC
November 2018

Defective mitochondrial and lysosomal trafficking in chorea-acanthocytosis is independent of Src-kinase signaling.

Mol Cell Neurosci 2018 10 3;92:137-148. Epub 2018 Aug 3.

Division of Neurodegenerative Diseases, Department of Neurology, Technische Universität Dresden, Dresden, Germany; Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, Dresden, Germany; German Center for Neurodegenerative Diseases (DZNE) Dresden, Dresden, Germany; Universitäts Centrum für seltene Erkrankungen, Technische Universität Dresden, Dresden, Germany. Electronic address:

Mutations in the VPS13A gene leading to depletion of chorein protein are causative for Chorea Acanthocytosis (ChAc), a rare devastating disease, which is characterized by neurodegeneration mainly affecting the basal ganglia as well as deformation of erythrocytes. Studies on patient blood samples highlighted a dysregulation of Actin cytoskeleton caused by downregulation of the PI3K pathway and hyper-activation of Lyn-kinase, but to what extent these mechanisms are present and relevant in the affected neurons remains elusive. We studied the effects of the absence of chorein protein on the morphology and trafficking of lysosomal and mitochondrial compartments in ChAc patient-specific induced pluripotent stem cell-derived medium spiny neurons (MSNs). Numbers of both organelle types were reduced in ChAc MSNs. Mitochondrial length was shortened and their membrane potential showed significant hyperpolarization. In contrast to previous studies, showing Lyn kinase dependency of ChAc-associated pathological events in erythrocytes, pharmacological studies demonstrate that the impairment of mitochondria and lysosomes are independent of Lyn kinase activity. These data suggest that impairment in mitochondrial and lysosomal morphologies in MSNs is not mediated by a dysregulation of Lyn kinase and thus the pathological pathways in ChAc might be - at least in part - cell-type specific.
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http://dx.doi.org/10.1016/j.mcn.2018.08.002DOI Listing
October 2018

Polycarboxylate-Templated Coordination Polymers: Role of Templates for Superprotonic Conductivities of up to 10  S cm.

Angew Chem Int Ed Engl 2018 05 18;57(22):6662-6666. Epub 2018 Apr 18.

Department of Chemistry, Indian Institute of Technology, Kharagpur, WB, 721302, India.

Three coordination polymers (CPs) have been synthesized based on a [Co(bpy)(H O) ] chain (bpy=4,4'-bipyridine) by a template approach. The frameworks are neutralized by different templated polycarboxylate anions (furan di-carboxylate (fdc) in Co-fdc, benzene tri-carboxylate (btc) in Co-tri and benzene tetra-carboxylate (btec) in Co-tetra). These templates with different degrees of protonation and ionic carrier concentration played significant role on crystal packing as well as formation of well-directed H-bonded networks which made these CPs perform well in proton conduction (PC). The PC value reaches to 1.49×10  S cm under 80 °C and 98 % relative humidity (R.H.) for Co-tri, which is the highest among CPs/MOFs/COFs and is an example of conductivity in the order of 10  S cm . Co-tri and Co-tetra are excellent proton conductors at mild temperature (40 °C) and 98 % R.H. (conductivities up to 2.92×10 and 1.38×10  S cm , respectively).
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http://dx.doi.org/10.1002/anie.201802632DOI Listing
May 2018

Calculation of linear and nonlinear optical properties of azobenzene derivatives with Kohn-Sham and coupled-cluster methods.

Phys Chem Chem Phys 2018 Mar;20(10):7303-7316

Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA.

Linear polarizabilities (α) and second hyperpolarizabilities (γ) of unsubstituted azobenzenes and 'push-pull' azobenzene derivatives are investigated using Kohn-Sham theory (KST) and coupled-cluster (CC) approaches. Various standard exchange-correlation functionals as well as a non-empirically 'tuned' long-range corrected (LC) functional with range-separated exchange are used in the KST calculations. When compared to correlated ab initio calculations and measurements, the tuned functional gives accurate low-energy excitation energies, especially for charge transfer (CT) transitions, and performs well for α. Basis set and solvent effects are also studied. In contrast to expectations, but in agreement with a prior study of π-conjugated systems that do not have low-energy CT excitations, the improvements of the CT excitation energies for the push-pull π-chromophores due to tuning do not go along with clear improvements of γ toward the CC reference data, likely due to the importance of the dynamic electron correlation for this property.
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http://dx.doi.org/10.1039/c7cp08655eDOI Listing
March 2018

A Moisture-Stable 3D Microporous Co -Metal-Organic Framework with Potential for Highly Selective CO Separation under Ambient Conditions.

Chemistry 2018 Apr 22;24(22):5982-5986. Epub 2018 Mar 22.

Department of Chemistry, Indian Institute of Technology Kharagpur, WB, 721302, India.

Selective adsorption and separation of CO from flue gas and landfill gas mixtures have drawn great attention in industry. Porous MOF materials are promising alternatives to achieve such separations; however, the stability in the presence of moisture must be taken into consideration. Herein, we have constructed a microporous metal-organic framework (MOF) {[Co(OBA)(L) ]⋅S} (IITKGP-8), by employing a V-shaped organic linker with an azo-functionalized N,N' spacer forming a 3D network with mab topology and 1D rhombus-shaped channels along the crystallographic 'b' axis with a void volume of 34.2 %. The activated MOF reveals a moderate CO uptake capacity of 55.4 and 26.5 cm  g at 273 and 295 K/1 bar, respectively, whereas it takes up a significantly lower amount of CH and N under similar conditions and thus exhibits its potential for highly selective sorption of CO with excellent IAST selectivity of CO /N (106 at 273 K and 43.7 at 295 K) and CO /CH (17.7 at 273 K and 17.1 at 295 K) under 1 bar. More importantly, this MOF exhibits excellent moisture stability as assessed through PXRD experiments coupled with surface area analysis.
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http://dx.doi.org/10.1002/chem.201800693DOI Listing
April 2018

Impaired DNA damage response signaling by FUS-NLS mutations leads to neurodegeneration and FUS aggregate formation.

Nat Commun 2018 01 23;9(1):335. Epub 2018 Jan 23.

Department of Neurology, Technische Universität Dresden, 01307, Dresden, Germany.

Amyotrophic lateral sclerosis (ALS) is the most frequent motor neuron disease. Cytoplasmic fused in sarcoma (FUS) aggregates are pathological hallmarks of FUS-ALS. Proper shuttling between the nucleus and cytoplasm is essential for physiological cell function. However, the initial event in the pathophysiology of FUS-ALS remains enigmatic. Using human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs), we show that impairment of poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response (DDR) signaling due to mutations in the FUS nuclear localization sequence (NLS) induces additional cytoplasmic FUS mislocalization which in turn results in neurodegeneration and FUS aggregate formation. Our work suggests that a key pathophysiologic event in ALS is upstream of aggregate formation. Targeting DDR signaling could lead to novel therapeutic routes for ameliorating ALS.
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http://dx.doi.org/10.1038/s41467-017-02299-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5780468PMC
January 2018

A Water-Stable Twofold Interpenetrating Microporous MOF for Selective CO Adsorption and Separation.

Inorg Chem 2017 Nov 1;56(22):13991-13997. Epub 2017 Nov 1.

Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721302, WB, India.

Self-assembly of bent dicarboxylate linker 4,4'-sulfonyldibenzoic acid (HSDB) and flexible N,N-donor spacer 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (L) with Co(NO)·6HO forms a twofold interpenetrated {[Co(SDB)(L)]·(HO)·(DMF)}, (IITKGP-6) network via solvothermal synthesis with sql(2,6L1) topology, which is characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, powder X-ray diffraction (XRD), and single-crystal XRD. The framework is microporous with a solvent-accessible volume of 25.5% and forms a one-dimensional channel along [1-1 0] direction with the dimensions of ∼3.4 × 5.0 Å. As the stability of metal-organic frameworks (MOFs) in the presence of water is a topic of significant importance while considering them for practical applications, this framework reveals its high stability toward water. The desolvated framework shows modest uptake of CO (50.6 and 37.4 cm g at 273 and 295 K under 1 bar pressure, respectively), with high selectivity over N and CH. Ideal adsorbed solution theory calculations show that the selectivity values of CO/N (15:85) are 51.3 at 273 K and 42.8 at 295 K, whereas CO/CH (50:50) selectivity values are 36 at 273 K and 5.1 at 295 K under 100 kPa. The high CO separation selectivity over N and CH along with its water stability makes this MOF a potential candidate for CO separation from flue gas mixture and landfill gas mixture as well.
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http://dx.doi.org/10.1021/acs.inorgchem.7b02136DOI Listing
November 2017

A microporous MOF with a polar pore surface exhibiting excellent selective adsorption of CO from CO-N and CO-CH gas mixtures with high CO loading.

Dalton Trans 2017 Nov;46(44):15280-15286

Department of Chemistry, Indian Institute of Technology Kharagpur, WB 721302, India.

A microporous MOF {[Zn(SDB)(L)]·S} (IITKGP-5) with a polar pore surface has been constructed by the combination of a V-shaped -SO functionalized organic linker (HSDB = 4,4'-sulfonyldibenzoic acid) with an N-rich spacer (L = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene), forming a network with sql(2,6L1) topology. IITKGP-5 is characterized by TGA, PXRD and single crystal X-ray diffraction. The framework exhibits lozenge-shaped channels of an approximate size of 4.2 × 5.6 Å along the crystallographic b axis with a potential solvent accessible volume of 26%. The activated IITKGP-5a revealed a CO uptake capacity of 56.4 and 49 cm g at 273 K/1 atm and 295 K/1 atm, respectively. On the contrary, it takes up a much smaller amount of CH (17 cm g at 273 K and 13.6 cm g at 295 K) and N (5.5 cm g at 273 K; 4 cm g at 295 K) under 1 atm pressure exhibiting its potential for a highly selective adsorption of CO from flue gas as well as a landfill gas mixture. Based on the ideal adsorbed solution theory (IAST), a CO/N selectivity of 435.5 and a CO/CH selectivity of 151.6 have been realized at 273 K/100 kPa. The values at 295 K are 147.8 for CO/N and 23.8 for CO/CH gas mixtures under 100 kPa. In addition, this MOF nearly approaches the target values proposed for PSA and TSA processes for practical utility exhibiting its prospect for flue gas separation with a CO loading capacity of 2.04 mmol g.
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http://dx.doi.org/10.1039/c7dt03341aDOI Listing
November 2017

A new set of Cd(ii)-coordination polymers with mixed ligands of dicarboxylate and pyridyl substituted diaminotriazine: selective sorption towards CO and cationic dyes.

Dalton Trans 2017 Aug;46(30):9901-9911

Department of Chemistry, Indian Institute of Technology Kharagpur, 721302, India.

On the basis of a mixed ligand system of L(NH) (6-(pyridin-4-yl)-1,3,5-triazine-2,4-diamine) and dicarboxylic acids, three new Cd(ii) coordination polymers viz. {[Cd(tdc)(L(NH))(HO)]·DMF·HO} (1), {[Cd(bdc)(L(NH))(HO)]·DMF·HO} (2), and {[Cd(ipa)(L(NH))(DMF)]·HO} (3) (tdcH = thiophene-2,5-dicarboxylic acid, bdcH = benzene-1,4-dicarboxylic acid, ipaH = benzene-1,3-dicarboxylic acid) were synthesized under diverse reaction conditions and characterized by single crystal X-ray diffraction, PXRD, elemental analysis, IR spectroscopy and TGA. While 1 and 2 revealed 1D chain structures, 3 acquired a 2D square net structural arrangement. Gas adsorption measurements of the desolvated framework 3 showed a moderate uptake of CO under ambient conditions with good selectivity over N and CH. The solid state luminescence properties were studied for all three coordination polymers. Moreover, a dye adsorption study on 3 exhibited selective adsorption towards a cationic dye.
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http://dx.doi.org/10.1039/c7dt01657cDOI Listing
August 2017

Neuronal Dysfunction in iPSC-Derived Medium Spiny Neurons from Chorea-Acanthocytosis Patients Is Reversed by Src Kinase Inhibition and F-Actin Stabilization.

J Neurosci 2016 11;36(47):12027-12043

Department of Neurology and

Chorea-acanthocytosis (ChAc) is a fatal neurological disorder characterized by red blood cell acanthocytes and striatal neurodegeneration. Recently, severe cell membrane disturbances based on depolymerized cortical actin and an elevated Lyn kinase activity in erythrocytes from ChAc patients were identified. How this contributes to the mechanism of neurodegeneration is still unknown. To gain insight into the pathophysiology, we established a ChAc patient-derived induced pluripotent stem cell model and an efficient differentiation protocol providing a large population of human striatal medium spiny neurons (MSNs), the main target of neurodegeneration in ChAc. Patient-derived MSNs displayed enhanced neurite outgrowth and ramification, whereas synaptic density was similar to controls. Electrophysiological analysis revealed a pathologically elevated synaptic activity in ChAc MSNs. Treatment with the F-actin stabilizer phallacidin or the Src kinase inhibitor PP2 resulted in the significant reduction of disinhibited synaptic currents to healthy control levels, suggesting a Src kinase- and actin-dependent mechanism. This was underlined by increased G/F-actin ratios and elevated Lyn kinase activity in patient-derived MSNs. These data indicate that F-actin stabilization and Src kinase inhibition represent potential therapeutic targets in ChAc that may restore neuronal function.

Significance Statement: Chorea-acanthocytosis (ChAc) is a fatal neurodegenerative disease without a known cure. To gain pathophysiological insight, we newly established a human in vitro model using skin biopsies from ChAc patients to generate disease-specific induced pluripotent stem cells (iPSCs) and developed an efficient iPSC differentiation protocol providing striatal medium spiny neurons. Using patch-clamp electrophysiology, we detected a pathologically enhanced synaptic activity in ChAc neurons. Healthy control levels of synaptic activity could be restored by treatment of ChAc neurons with the F-actin stabilizer phallacidin and the Src kinase inhibitor PP2. Because Src kinases are involved in bridging the membrane to the actin cytoskeleton by membrane protein phosphorylation, our data suggest an actin-dependent mechanism of this dysfunctional phenotype and potential treatment targets in ChAc.
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http://dx.doi.org/10.1523/JNEUROSCI.0456-16.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6604921PMC
November 2016

Copper-Catalyzed Regioselective Cascade Alkylation and Cyclocondensation of Quinoline N-Oxides with Diazo Esters: Direct Access to Conjugated π-Systems.

Chemistry 2016 Sep 12;22(39):13826-13830. Epub 2016 Aug 12.

Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.

An inexpensive copper-catalyzed cascade regioselective alkylation, followed by cyclocondensation of quinoline N-oxides with α-diazo esters has been achieved successfully to provide heteroarene-containing conjugated π-systems. The developed method is simple, straightforward, and economical with a broad range of substrate scope. The dual role of copper catalyst in the C-H bond functionalization and in Lewis acid-promoted cyclization was explored.
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http://dx.doi.org/10.1002/chem.201602493DOI Listing
September 2016

Quantum chemical investigation of meta-xylylene based one-dimensional polymer chain.

J Phys Chem A 2015 Mar 25;119(10):2176-85. Epub 2015 Feb 25.

Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India.

We have investigated unsubstituted and methyl substituted polyradical chains of meta-xylylene by using density functional theory-broken symmetry methodology (DFT-BS). Optimization of geometry in the high-spin and low-spin states have been done at B3LYP/6-31G(d,p) and M06-2X/6-31G(d,p) levels in unrestricted methodology. Single-point calculations on the high-spin optimized geometries have been done by using the 6-311G(d,p) basis set. Each polyradical has been found to be nonplanar with a high-spin ground state. Each has a coupling constant larger than thermal energy. For each group of polyradicals, the coupling constant has been found to exponentially decrease with increase in the number of phenylene groups. The B3LYP infinite chain limit has been estimated for both the unsubstituted and substituted polyradicals. The individual inter-radical-site coupling constants have been estimated for the triradicals and tetraradicals using HDVV Hamiltonian in ORCA 3.0.1 code. These are also generally large and positive, revealing a strong intersite ferromagnetic interaction. The intersite coupling constant too decreases with increasing distance between the radical centers. Finally, we have used CRYSTAL09 package for calculations on the infinitely long one-dimensional and periodic polyradical chains. The coupling constants estimated from the periodic calculations are quite large at about 500 cm(-1) and somewhat greater than the limiting values calculated for the polyradicals with an increasing number of phenylene groups. This happens as the individual polyradicals of increasing size progressively deviate from periodicity, and thereby lessens the strength of through-bond spin-spin coupling. The calculated band gap of ∼4.5 eV indicates that the infinitely long one-dimensional chains must be ferromagnetic and electron insulators.
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http://dx.doi.org/10.1021/acs.jpca.5b01081DOI Listing
March 2015

The Triplet-Singlet Gap in the m-Xylylene Radical: A Not So Simple One.

J Chem Theory Comput 2014 Jan;10(1):335-45

Departament de Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona , C/Martí i Franquès 1, E-08028 Barcelona, Spain.

Meta-benzoquinodimethane (MBQDM) or m-xylylene provides a model for larger organic diradicals, the triplet-singlet gap being the key property. In the present work this energy difference has been the object of a systematic study by means of several density functional theory-based methods including B3LYP, M06, M06-2X, HSE and LC-ωPBE potentials and a variety of wave function-based methods such as complete active space self consistent field (CASSCF), Multireference second-order Møller-Plesset (MRMP), difference dedicated configuration interaction (DDCI), and Multireference configuration interaction (MRCI). In each case various basis sets of increasing quality have been explored, and the effect of the molecular geometry is also analyzed. The use of the triplet and broken symmetry (BS) solutions for the corresponding optimized geometries obtained from B3LYP and especially M06-2X functionals provide the value of the adiabatic triplet-singlet gap closer to experiment when compared to the reported value of Wenthold, Kim, and Lineberger, (J. Am. Chem. Soc. 1997, 119, 1354) and also for the electron affinity. The agreement further improves using the full π-valence CASSCF(8,8) optimized geometry as an attempt to correct for the spin contamination effects on the geometry of the BS state. The CASSCF, MRMP, and MRCI, even with the full π valence CAS(8,8) as reference and relatively large basis set, systematically overestimate the experimental value indicating either that an accurate description must go beyond this level of theory, including σ electrons and higher order polarization functions, or perhaps that the measured value is affected by the experimental conditions.
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http://dx.doi.org/10.1021/ct400883mDOI Listing
January 2014

Theoretical investigation of photomagnetic properties of oxoverdazyl-substituted pyrenes.

J Phys Chem A 2013 Sep 6;117(36):8609-22. Epub 2013 May 6.

Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.

We have investigated the ground state spin of 10 pairs of possible photochromic diradical isomers by quantum chemical methods. Dihydrogen pyrenes and dinitrile pyrenes have been chosen as spacers with radical centers attached at (1,7) and (1,8) locations. Oxoverdazyl has served as a radical center, and both C and N linkages have been investigated. Triplet molecular geometries have been optimized at the UB3LYP/6-311G(d,p) level. Single-point calculations on triplet and broken symmetry states have been performed using the 6-311++G(d,p) basis set. Careful designs have led to the prediction of strongly coupled dihydropyrene (DHP) isomers, and the cyclophenadiene (CPD) isomers have always been found as weakly coupled. The effect of the functional M06-2X has been investigated. Calculated TDDFT spectra have been sufficient to guarantee photochromism of the designed diradicals. It has been estimated that compounds of diradicals with large coupling constants in the DHP form would show a pronounced change in molar susceptibility on photoconversion. This has led us to identify two molecules that can serve as a photomagnetic switch at room temperature.
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http://dx.doi.org/10.1021/jp402756jDOI Listing
September 2013