Roles of various bridges on intramolecular charge Transfers, dipole moments and first hyperpolarizabilities of Donor-Bridge-Acceptor types of organic Chromophores: Theoretical assessment using Two-State model

Planar in Brooker's mode and twisted in Reichardt's mode: defying the steric forces in biphenyl types of zwitterionic systems through metameric resonance stabilizations

“…From a thorough look at the numerous examples of biphenyl types of systems reported in the literature, I have observed one thing which is that when the biphenyls are para substituted (like donor–acceptor substituted or push–pull types of biphenyl systems), reduced values of twist angles are reported, compared to the unsubstituted biphenyl types of systems. 50,51 Hence, one can say that chemical perturbation induced by donor/acceptor substitutions is capable of reducing the twist angle to some extent. Based on this observation I can conjecture that if large chemical perturbations (for example, charged donor/acceptor systems like zwitterions) can be induced in the biphenyl types of systems, then one can possibly be able to achieve planarity or pseudo planarity types of conformations.…”

Synthesis, nonlinear optical analysis and DFT studies of D–π–D and A–π–A configured Schiff bases derived from bis-phenylenediamine

“…[11][12][13] The unique property of NLO materials is the transfer of intramolecular charge transfer (ICT) from electron donating to electron accepting moieties through conjugation links. [14][15][16] Experimental and computational data suggest that introducing strong donor (D) and acceptor (A) parts on paradoxical edges of the spacer, i.e., D-A, D-D-A, and A-D-A, can result in a broad second-order NLO response. 13 Charge transfer is improved in compounds containing delocalized electrons in a D-A conguration.…”

A theoretical comparison of the electrical and nonlinear optical properties ofGDY–π–TPA: The important role ofπ‐conjugated bridge

“…The β 0 values of our systems are comparable to the values (about 2.0 Â 10 4 a.u.) of some organic chromophores with hetero-aromatic bridges (diazine, tetrazine, pyrrole, furan, and thiophene) and conjugated bridges (ethylene and acetylene) [12,21].…”

“…For example, at the CNDOVSB theoretical level, heterocycles (furan, pyrrole, and thiophene) decorated with donor/acceptor groups (NMe 2 /NO 2 ) have large first hyperpolarizabilities (β 0 ) in a range of 12.9 Â 10 À30 to 13.5 Â 10 À30 cm 5 e.s.u [20]. Sanyasi Sitha et al have performed computational studies to account for the roles of various bridges (such as aromatic rings, ethylene, and acetylene) on the β 0 values of D-bridge-A types of organic chromophores, with p-aniline as the donor and p-nitrobenzene as the acceptor [12,21]. Recently, it has been reported that some molecules containing -CH=CH) nbridges can exhibit large first hyperpolarizabilities [22,23].…”

“…To explore the effect of different conjugated bridges on the NLO response and to simplify calculations, we only selected typical electron-rich (pyrrole, furan, and thiophene) and electron-deficient (tetrazine, diazine, and pyridine) heterocycles as π-conjugated bridges. In addition, ethylene and acetylene also became our subjects as they are excellent conjugated bridges for designing NLO molecules [21]. Choosing these π-conjugated bridges can systematically determine the contribution of π-conjugated bridges to the NLO response of the system.…”