In this present work, four novel molecules (BPN, BPNS, BPS, and BPSN), possessing excited-state intramolecular proton transfer (ESIPT) characteristics, were designed to quantify the impacts of substituent effects on their photophysical properties. By exploring the primary geometrical parameters concerning hydrogen bonds, it should be noticed that the intramolecular hydrogen bonds (IHBs) of the studied molecules have been strengthened at S state. Infrared vibrational spectra analysis illustrates that adding electron-donating group thiophene to the proton donor side can weaken the IHBs in comparison to the electron-withdrawing group pyridine.