Publications by authors named "H P Rohr"

209 Publications

Isoreticular Chemistry of Group 13 Metal-Organic Framework Compounds Based on V-Shaped Linker Molecules: Exceptions to the Rule?

Inorg Chem 2021 Jun 9;60(12):8861-8869. Epub 2021 Jun 9.

Institute of Inorganic Chemistry, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany.

Following the concept of isoreticular chemistry, we carried out a systematic study on Ga-containing metal-organic frameworks (MOFs) using six V-shaped linker molecules of differing sizes, geometries, and additional functional groups. The linkers included three isophthalic acid derivatives (-HBDC-R, R = CH, OCH, NHCOCH), thiophene-2,5-dicarboxylic acid (HTDC), and two 4,4'-sulfonyldibenzoic acid derivatives (HSDBA, DPSTA). The crystal structures of seven compounds were elucidated by a combination of model building, single-crystal X-ray diffraction (SCXRD), three-dimensional electron diffraction (3D ED), and Rietveld refinements against powder X-ray diffraction (PXRD) data. Four new Ga-MOFs that are isoreticular with their aluminum counterparts, i.e. Ga-CAU-10-R (Ga(OH)(-BDC-R); R = OCH, NHCOCH), Ga-CAU-11 (Ga(OH)(SDBA)), and Ga-CAU-11-COOH (Ga(OH)(HDPSTC)), were obtained. For the first time large single crystals of a MOF crystallizing in the CAU-10 structure type could be isolated, i.e. Ga-CAU-10-OCH, which permitted a detailed structural characterization. In addition, the use of 5-methylisophthalic acid and thiophene-2,5-dicarboxylic acid resulted in two new Ga-MOFs denoted Ga-CAU-49 and Ga-CAU-51, respectively, which are not isostructural with any known Al-MOF. The crystal structure of Ga-CAU-49 ([Ga(-HBDC-CH)(-BDC-CH)(OH)(HO)]) contains an unprecedented rod-shaped inorganic building unit (IBU) of the formula {Ga(OH)O}, composed of corner-sharing GaO and GaO polyhedra. In Ga-CAU-51 ([Ga(OH)(CHOS)]) chains of alternating and corner-sharing GaO polyhedra form the IBU. A detailed characterization of the title compounds was carried out, including nitrogen gas and water vapor sorption measurements. Ga-CAU-11 was the only compound exhibiting porosity toward nitrogen with a type I isotherm, a specific surface area of = 210 m/g, and a micropore volume of = 0.09 cm/g. The new MOF Ga-CAU-51 exhibits exceptional water sorption properties with a reversible S-shaped isotherm and a high uptake around / = 0.38 of = 370 mg/g.
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http://dx.doi.org/10.1021/acs.inorgchem.1c00767DOI Listing
June 2021

Mono- and di(dimethylamino)styryl-substituted borondipyrromethene and borondiindomethene dyes with intense near-infrared fluorescence.

Chem Asian J 2006 Jul;1(1-2):176-87

Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China.

Four novel borondipyrromethene (BDP) and -diindomethene (BDI) dyes with one or two (dimethylamino)styryl extensions at the chromophore were synthesized and spectroscopically investigated. An X-ray crystal structure shows that the extended auxochrome is virtually planar. All dyes thus display intense red/near infrared (NIR) absorption and emission. The (dimethylamino)styryl group induces a charge-transfer character that entails bright solvatochromic fluorescence, which is only quenched with increasing solvent polarity according to the energy-gap law. The dye with an additional dimethylanilino group at the meso position of BDP shows a remarkable switching of lipophilicity by protonation. Two dyes with an 8-hydroxyquinoline ligand at the meso position display quenched emission in the presence of Hg2+ or Al3+ owing to electron transfer from the excited BDP to the complexed receptor. The BDI dye presents a pH indicator with bright fluorescence and extremely low fluorescence anisotropy.
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http://dx.doi.org/10.1002/asia.200600042DOI Listing
July 2006

[The bait must please the fish and not the fisherman].

Authors:
Hanspeter Rohr

Praxis (Bern 1994) 2006 Dec;95(51-52):2043-6

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December 2006

Proton- and redox-controlled switching of photo- and electrochemiluminescence in thiophenyl-substituted boron-dipyrromethene dyes.

Chemistry 2006 Jan;12(3):689-700

Div. I.3, Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany.

A luminescent molecular switch in which the active thiol/disulfide switching element is attached to a meso-phenyl-substituted boron-dipyrromethene (BDP) chromophore as the signalling unit is presented. The combination of these two functional units offers great versatility for multimodal switching of luminescence: 1) deprotonation/protonation of the thiol/thiolate moiety allows the highly fluorescent meso-p-thiophenol-BDP and its nonfluorescent thiolate analogue to be chemically and reversibly interconverted, 2) electrochemical oxidation of the monomeric dyes yields the fluorescent disulfide-bridged bichromophoric dimer, also in a fully reversible process, and 3) besides conventional photoexcitation, the well separated redox potentials of the BDP also allow the excited BDP state to be generated electrochemically (i.e., processes 1) and 2) can be employed to control both photo- and electrochemiluminescence (ECL) of the BDP). The paper introduces and characterizes the various states of the switch and discusses the underlying mechanisms. Investigation of the ortho analogue of the dimer provided insight into potential chromophore-chromophore interactions in such bichromophoric architectures in both the ground and the excited state. Comparison of the optical and redox properties of the two disulfide dimers further revealed structural requirements both for redox switches and for ECL-active molecular ensembles. By employing thiol/disulfide switching chemistry and BDP luminescence features, it was possible to create a prototype molecular ensemble that shows both fully reversible proton- and redox-gated electrochemiluminescence.
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http://dx.doi.org/10.1002/chem.200500729DOI Listing
January 2006

Multiple switching and photogated electrochemiluminescence expressed by a dihydroazulene/boron dipyrromethene dyad.

Angew Chem Int Ed Engl 2005 Oct;44(42):6943-7

Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.

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http://dx.doi.org/10.1002/anie.200501573DOI Listing
October 2005
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