Chemical redox-induced chiroptical switching of supramolecular assemblies of viologens

Chiral assemblies of viologen-modified glutamide derivatives exhibit a unique orange-color and CD signals by CT complexes of viologen groups and electro-responsive chiroptical switching behaviors in the visible region in water.

New Charge Transfer Complexes of K+-Channel-Blocker Drug (Amifampridine; AMFP) for Sensitive Detection: Solution Investigations and DFT Studies

UV–Vis spectroscopy was used to investigate two new charge transfer (CT) complexes formed between the K+-channel-blocker amifampridine (AMFP) drug and the two π-acceptors 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetracyanoethylene (TCNE) in different solvents. The molecular composition of the new CT complexes was estimated using the continuous variations method and found to be 1:1 for both complexes. The formed CT complexes’ electronic spectra data were further employed for calculating the formation constants (KCT), molar extinction coefficients (εCT), and physical parameters at various temperatures, and the results demonstrated the high stability of both complexes. In addition, sensitive spectrophotometric methods for quantifying AMFP in its pure form were proposed and statistically validated. Furthermore, DFT calculations were used to predict the molecular structures of AMFP–DDQ and AMFP–TCNE complexes in CHCl3. TD-DFT calculations were also used to predict the electronic spectra of both complexes. A CT-based transition band (exp. 399 and 417 nm) for the AMFP–TCNE complex was calculated at 411.5 nm (f = 0.105, HOMO-1 → LUMO). The two absorption bands at 459 nm (calc. 426.9 nm, f = 0.054) and 584 nm (calc. 628.1 nm, f = 0.111) of the AMFP–DDQ complex were theoretically assigned to HOMO-1 → LUMO and HOMO → LUMO excitations, respectively.

Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

Functionalized naphthalenediimides based supramolecular charge–transfer complexes via self-assembly and their photophysical properties†

We report here the design and syntheses of a naphthalenediimide (NDI)-N functionalized organic fluorophore, 1 and its supramolecular CT complexes [(1∙2H)2+·(PA–)2] (2) and [(1∙2H)2+·(3,5-DNSA–)2] (3), self-assembled from 1 as an...

Molecular conductors composed from Organic-Transistor Materials

Assistant Professor Tomofumi Kadoya is part of a team within the Graduate School of Material Science at the University of Hyogo in Japan. He is engaged with a range of different investigations related to conductive organic materials. One of the main focuses of Kadoya's research is organic transistors and organic charge-transfer (CT) complexes. CT complexes achieve conductivity by chemical doping but in organic transistors, conduction carriers are generated by field effect, where an electric field is used to control the flow of current. Among the many goals of the research, Kadoya and his team want to increase the methods and types of organic doping.

Electron-transfer complexation of morpholine donor molecule with some π – acceptors: Synthesis and spectroscopic characterizations

Morpholine is an interesting moiety that used widely in several organic syntheses. The intermolecular charge-transfer (CT) complexity associated between morpholine (Morp) donor with (monoiodobromide “IBr”, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone “DDQ”, 2,6-dichloroquinone-4-chloroimide “DCQ” and 2,6-dibromoquinone-4-chloroimide “DBQ”) π–acceptors have been spectrophotometrically investigated in CHCl3 and/or MeOH solvents. The structures of the intermolecular charge-transfer (CT) were elucidated by spectroscopic methods like, infrared spectroscopy. Also, different analyses techniques such as UV-Vis and elemental analyses were performed to characterize the four morpholine [(Morp)(IBr)], [(Morp)(DDQ)], [(Morp)(DCQ)] and [(Morp)(DBQ)] CT-complexes which reveals that the stoichiometry of the reactions is 1:1. The modified Benesi-Hildebrand equation was utilized to determine the physical spectroscopic parameters such as association constant (K) and the molar extinction coefficient (ε).

Formation of charge transfer complex between metalloporphyrins and aromatic solvents in tetrahydrofuran media: A density functional study

We have investigated the possible formation of charge transfer (CT) complexes of metallotetraphenylporphyrins (MTPhP with M = Mn, Fe, Co, Ni and Cu) and metallooctaethylporphyrins (MOEtP with M = Mn, Fe, Co, Ni, Cu and Zn) with the aromatic solvents, namely benzene, chlorobenzene, benzonitrile and toluene, respectively, in the tetrahydrofuran (THF) media. We have carried out energy minimization calculations of the hybrid systems (metalloporphyrins and aromatic solvents) in 1:1 and 1:2 stoichiometry in presence of THF media. We have analyzed the role of metal present in the metalloporphyrin in the formation of complexes for both 1:1 and 1:2 stoichiometry. Our analysis reveals that the MTPhP-solvent hybrid system is more stable compared to the MOEtP-solvent hybrid system.

Exciton funneling in light-harvesting organic semiconductor microcrystals for wavelength-tunable lasers

Organic solid-state lasers are essential for various photonic applications, yet current-driven lasing remains a great challenge. Charge transfer (CT) complexes formed with p-/n-type organic semiconductors show great potential in electrically pumped lasers, but it is still difficult to achieve population inversion owing to substantial nonradiative loss from delocalized CT states. Here, we demonstrate the lasing action of CT complexes based on exciton funneling in p-type organic microcrystals with n-type doping. The CT complexes with narrow bandgap were locally formed and surrounded by the hosts with high-lying energy levels, which behave as artificial light-harvesting systems. Excitation light energy captured by the hosts was delivered to the CT complexes, functioning as exciton funnels to benefit lasing actions. The lasing wavelength of such composite microcrystals was further modulated by varying the degree of CT. The results offer a comprehensive understanding of exciton funneling in light-harvesting systems for the development of high-performance organic lasing devices.