Search

Sufficiently strong molecular magnets are used in small modern electronic and spintronic devices. Diradical organic magnetic molecules (OMMs) are promising options due to their lightness, flexibility, and the low energy required for their synthesis. In this field, the coupler is a dominating component, though acetylene, the shortest coupler, has not been studied for this use. In this study, we conceptualize several model systems using an acetylene link to couple different monoradicals. We simulated their magnetic strength using the broken symmetry method via density functional theory calculations. Our results show that the acetylene (–C≡C–) coupler gives much larger J values than the ethylene (–C＝C–) coupler. Acetylene coupling a phenoxyl (PO) and a nitronyl nitroxide (NN) diradical is the strongest ferromagnetic diradical OMM, and acetylene coupling a PO bisradical is the strongest anti-ferromagnetic diradical OMM. Moreover, we found that the magnetic strength is dependent on the coupler length and torsion, but is independent of the bending. Since only a very small energy barrier is needed, it is feasible to use torsion to tune a diradical OMM's magnetic strength. Our results are also beneficial for the rational design and synthesis of diradical OMMs. [ABSTRACT FROM AUTHOR]

Accurate quantum computational chemistry has evolved dramatically. The size of molecular systems, which can be studied accurately using molecular theory, is increasing very rapidly. Theoretical chemistry has opened up a world of new possibilities. It can treat real systems with predictable accuracy. Computational chemistry is becoming an integral part of theoretical and experimental research in chemical science. In this paper, we will review our recent developments in the theoretical and computational study on some very interesting subjects such as fluorescent fluoride sensor, "on–off" molecular switch, electron transport through π-stacking, and molecular electronic device on the basis of the molecular functional levels. We provide a brief introduction about the importance of all these systems in the present scenario of scientific activity and the numerical results and discussion in the light of experimentally found results. We have enjoyed good progress in each of the above areas. We are very excited about our discoveries in each field and would like to share this enthusiasm with readers. [ABSTRACT FROM AUTHOR]

A rationally designed, coumarin-based fluorescent sensor imino-coumarin (IC) displays high selectivity for Cu2+over a variety of competing metal ions in aqueous solution with a significant fluorescence increase. DFT/TDDFT calculations support that the fluorescence ‘turn-on’ of ICoriginates from blocking the electron transfer of the nitrogen lone pair upon complexation with Cu2+. ICwas successfully applied to microscopic imaging for detection of Cu2+in LLC-MK2 cells (in vitro) and several living organs (in vivo). [ABSTRACT FROM AUTHOR]

An indole conjugated coumarin 1for KCN chemodosimeter has been prepared and displayed considerable dual changes in both absorption (blue-shift) and emission (turn-on) bands exclusively for KCN. DFT/TDDFT calculations support that the fluorescence enhancement of 1-KCN is mainly due to blocking of the ICT process. [ABSTRACT FROM AUTHOR]

Novel,stimulus-responsive supramolecular structures in the formof fibers, gels, and spheres, derived from an azobenzene-containingbenzenetricarboxamide derivative, are described. Self-assembly oftris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxamide(Azo-1) in aqueous organic solvent systems results insolvent dependent generation of microfibers (aq DMSO), gels (aq DMF),and hollow spheres (aq THF). The results of a single crystal X-raydiffraction analysis of Azo-1(crystallized from a mixtureof DMSO and H2O) reveal that it possesses supramolecularcolumnar packing along the baxis. Data obtainedfrom FTIR analysis and density functional theory (DFT) calculationsuggest that multiple hydrogen bonding modes exist in the Azo-1fibers. UV irradiation of the microfibers, formed in aq DMSO, causescomplete melting while regeneration of new fibers occurs upon visiblelight irradiation. In addition to this photoinduced and reversiblephase transition, the Azo-1supramolecules display areversible, fiber-to-sphere morphological transition upon exposureto pure DMSO or aq THF. The role played by amide hydrogen bonds inthe morphological changes occurring in Azo-1is demonstratedby the behavior of the analogous, ester-containing tris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxylate (Azo-2) and by the hydrogen abstraction in the presence offluoride anions. [ABSTRACT FROM AUTHOR]

A new series of neutral radicals (DP1–DP6) based on diazaphenalenyl were designed via heteroatomic modifications. As spin sources, the designed radicals were implemented in four different diradical model systems (models I, II, III, and IV) by changing the reference radical and the linkage, and their magnetic interactions between the designed radicals and the reference radical were investigated by using density functional theory calculations. The trend in strength of magnetic interactions of radicals was found to be identical in different model systems. The strength of magnetic interactions could be understood by spin density distributions and NICS values. Our results will be helpful in designing and controlling the organic magnetic materials incorporated with diazaphenalenyl derivatives. In particular, as a new family of spin source radical, DP3could be a potential candidate in designing new organic magnetic materials due to its strong magnetic coupling and high stability in diradical systems. [ABSTRACT FROM AUTHOR]

Abstract: A series of blue fluorescent 9,9-diethyl-2,7-distyryl-9H-fluorene derivatives with various capping moieties such as diphenylamino; diphenylphosphino; triphenylsilyl; phenoxy; phenylmercapto; phenylselenoxy; and triphenymethyl groups were synthesized using the Honor–Emmons reaction. The highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels were characterized with a photoelectron spectrometer and rationalized with quantum mechanical density functional theory calculations. The electroluminescent properties were explored through the fabrication of multilayer devices with a structure of Indium-tin-oxide/N,N′-diphenyl-N,N′-(1-napthyl)-(1,1′-phenyl)-4,4′-diamine/2-methyl-9,10-di(2-naphthyl)anthracene:blue dopants (5–15wt.%)/4,7-diphenyl-1,10-phenanthroline/lithium quinolate/Al. All devices, except that using NPh2, exhibited a Commission Internationale de I''Eclairage (CIE) y value less than 0.19. The best luminous efficiency of 3.87cd/A and external quantum efficiency of 2.65% at 20mA/cm2 were obtained in a device comprising the 4-phenylsulfanyl capped 9,9-diethyl-2,7-distyrylfluorene derivative with CIE coordinates (0.16, 0.18). [Copyright &y& Elsevier]