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Spectroscopic properties of push-pull 2-(4-carboxyphenyl)-6-dimethylaminobenzothiazole derivatives in solution and the solid state
摘要： 6-Dimethylamino-2-phenylbenzothiazoles with a carboxy, ester and amide substituent on the 2-phenyl group were prepared as a series of the push-pull benzothiazoles, and their spectroscopic and photophysical properties in solutions were investigated. The derivatives showed solvatochromic fluorescence with quantum yields over 0.68 in various organic solvents similar to the core fluorophore structure. The color variation ranges in fluorescence solvatochromism of the derivatives were wider than that of the original compound having the core structure, 6-dimethylamino-2-phenylbenzothiazole. It was also found that the derivatives together with the original compound show solid state fluorescence depending on their crystal structures. In particular, an ester derivative with a protected serine has a reasonable crystal packing leading to increase in fluorescence efficiency. The results of the present study provide a guide to design push-pull 2-phenylbenzothiazoles exhibiting fluorescence in solution and the solid state.
关键词： Substituent effect,Firefly oxyluciferin,Fluorescence solvatochromism,Solid state fluorescence,Benzothiazole
更新于2025-11-19 16:56:35
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Mechanofluorochromism based on BOPIM complexes: The effect of substituents and regulation of the direction of the emission color changes
摘要： Novel boron 2-(2′-pyridyl)imidazole (BOPIM) complexes T1, T2 and T3 with different substituents (including bromo, tert-butyl and methoxyl) on the benzene ring of BOPIM dyes have been designed and synthesized, and their optical properties in both solution and the solid state were investigated and compared. The three compounds exhibited typical intramolecular charge transfer (ICT) characteristics. Solvent-dependent UV-vis absorption, fluorescence emission spectra and quantum chemical calculation indicated a molecular push-pull electronic structure. Their ICT degrees increased with the sequence of T1 < T2 < T3. The analysis of the X-ray crystal structure revealed the twisted molecular conformation of BOPIM dyes. Furthermore, they showed remarkable reversible mechanofluorochromic (MFC) features under mechanical force. It was found that the MFC activities could be tuned easily by changing the substituents on the BOPIM dyes. T1 exhibited emission color change from bright green to yellowish green with a spectral red-shift of only 22 nm under mechanical stimuli, whereas T2 and T3 gave the large spectral red-shifts of 36 and 30 nm. Electronic and steric effects of the substitutes were proved playing significant roles in regulating the ICT effect and intermolecular interactions. More importantly, the remarkable effect of substituents on the MFC behaviors of BOPIM dyes will provide an effective way to obtain novel high-contrast MFC dyes.
关键词： Mechanofluorochromism,Substituent effect,Intramolecular charge transfer,Solid-state fluorescence,BOPIM complexes
更新于2025-11-14 15:26:12
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Electrochemistry of zinc tetraarylporphyrins containing fused butano and benzo groups. Effect of solvent and substituents on spectra, potentials and mechanism in nonaqueous media
摘要： Two series of zinc tetraarylporphyrins containing four b,b′-pyrrole fused butano or benzo groups were synthesized and characterized as to their electrochemical and spectroelectrochemical properties in nonaqueous media. The examined compounds are represented as butano(Ar)4PorZn and benzo(Ar)4PorZn, where Por is the porphyrin dianion and Ar is a p-CH3Ph, Ph or p-ClPh substitutent on meso-positions of the macrocycle. Each Zn(II) butano- and benzoporphyrin undergoes two one-electron reductions to give a p-anion radical and dianion in CH2Cl2. In contrast, three reductions were observed for the benzoporphyrin derivatives in pyridine, the third of which is assigned as electron addition to a benzophlorin anion generated from the doubly reduced benzoporphyrin. Two overlapped one-electron oxidations were observed for the butanoporphyrins in CH2Cl2, a result not previously observed for any other zinc porphyrin. The electrochemically measured HOMO–LUMO gap of the benzoporphyrins ranges from 1.89 to 1.90 V in CH2Cl2 and from 1.93 to 1.95 V in pyridine. Both values are smaller than the gaps of butanoporphyrins at 2.11–2.13 V in CH2Cl2 and 2.07–2.09 V in pyridine.
关键词： spectroelectrochemistry,electrochemistry,substituent effect,synthesis,porphyrinoids
更新于2025-09-10 09:29:36
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Deciphering the multifarious charge transport behaviour of crystalline propeller-shaped triphenylamine analogues
摘要： A collection of para-substituted propeller-shaped triphenylamine (TPA) derivatives have been computationally investigated for the charge transport characteristics exhibited by the derivatives using the Marcus-Hush formalism. The various substituents chosen in the current work, having features that range from electron withdrawing to electron donating nature, play a key role in defining the reorganization energy and electronic coupling properties of the TPA derivatives. TPA moiety is expected to possess weak electronic coupling on the basis of poor orbital overlap upon aggregation owing to the restriction imposed by the propeller shape of the triphenylamine core. However, the substituent groups attached to the TPA core can significantly dictate the crystal packing motif of the TPA derivatives, wherein the variety of noncovalent intermolecular interactions subsequently generated drive the packing arrangement and influence the electronic coupling between the neighbouring orbitals. The intermolecular interactions in the crystalline architecture of TPA derivatives were probed using Hirshfeld and QTAIM techniques. Furthermore, SAPT analysis of the TPA analogues has revealed that a periodic arrangement of energetically stable dimers having significant electronic coupling is essential in order to contribute a high charge carrier mobility to the overall crystal.
关键词： SAPT,Pi stacking,1-D charge transport pathway,Marcus-Hush formalism,Substituent effect
更新于2025-09-09 09:28:46
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Substituent Effect on Metastable‐State Photoacids: Design, Synthesis and Evaluation of their Photochemical Properties
摘要： Recently, metastable-state photoacids have been widely used to control proton transfer in numerous chemical and biological processes as well as applications with visible light. Generally, substituent groups have great influence on photochemical properties of molecules, which will further affect their applications. Yet, substituent effect on the metastable-state photoacid has not been studied systematically. In this work, sixteen metastable-state photoacid derivatives were designed and synthesized based on their substituents involving a large range of σ-π electron-donor-acceptor capability. Substituent effects main on their color display (or maximum absorption peak(s)), solubility, pKa(s), dark-/photo-acidity, photosensitivity and relaxation kinetic(s) were investigated in detail. This study will be conducive to targetedly design and synthesize promising photoacids as well as to apply their photo-controlled proton-release processes in functional materials/devices.
关键词： visible-light-response,metastable-state photoacid,pH photocontrol,substituent effect,chemical dynamics
更新于2025-09-09 09:28:46
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Fluorescence Behavior of Bis(cyanostyryl)pyrrole Derivatives Depending on Substituent Position of Cyano Groups in Solution and in Solid State
摘要： We synthesized a novel fluorophores of distyrylpyrrole derivatives possessing cyano groups at different position on olefin. Their fluorescence properties in solution and solid state were investigated by photoluminescence quantum yield and lifetime measurement, which provided radiative decay constant (kf) and nonradiative decay constant (knr). The derivative with cyano groups at inner position of molecule, inner isomer, shows high fluorescence quantum yield (Φf = 0.43) in solution while another derivative with cyano group at outer position, outer isomer, hardly shows fluorescence (Φf < 0.01) due to the large nonradiative decay (knr > 10 ns?1). Upon formation of single crystal or nanoparticles, these difference were inverted; the quantum yield of outer and inner isomer was enhanced and diminished, respectively. We explained these differences between in solution and solid state by means of analysis of single X-ray structure and computation study.
关键词： solid emission,pyrrole derivatives,substituent effect,Solid-state luminescence enhancement
更新于2025-09-04 15:30:14