Theoretical study of static (Hyper)polarizabilities of twisted intramolecular charge transfer chromophores

Abstract

Density functional theory calculations are performed to study the (hyper)polarizabilities of a series of planar and twisted intramolecular charge transfer molecules (tictoids) with different electron-donating and electron-withdrawing groups. Both similarity and difference between the planar and twisted molecules are noted in their (hyper)polarizability variation with respect to substituent and solvent dielectric constant. When compared with dramatic enhancements resulting from geometry twist and solvent effect, substitution to D/A pairs leads to relatively moderate variation in (hyper) polarizability. In addition, tictoids with different substituents may exhibit different solvent effects in their hyperpolarizability magnitudes. Our calculations suggest that the nonlinear optical response of the tictoids could be tuned by appropriately selecting the donor/acceptor pairs and solvents.

Conformational analysis of some pyridinium phenolates and synthetic precursors based on X-ray and IR characterisations

“…a) Calculated angles in solution (in gas phase). b) BLA = [(B3-B2)+(B5-B6)+(B7-B6)]/3 (reference 25 ). c) Calculated values.…”

“…Calculated aromatic bond lengths of 1a are alternately shorter or longer 3,25,27 than those derived from X-ray analysis ( Table 1, The fact, that quadratic hyperpolarisability β has been correlated to the bond length alternation (BLA) parameter, [28][29][30][31] prompted us to investigate it for representative molecules reported in Table 1. BLA is defined as the average length differences between single and double bonds in polyene chains.…”

“…In particular, sustained efforts have been exerted to design chromophores with ever-stronger NLO responses. 3,6,8,[11][12][13][21][22][23][24][25] Recently, the synthesis of 5 and 6 crowed by four methyl groups at ortho-ortho' positions of the intercyclic bond was achieved (Scheme 3). [11][12][13] Unfortunately, the too low solubility of 5 makes its NLO characterization impossible.…”

A quantitative analysis of intramolecular charge transfer contribution to polarizability responses in donor-π-acceptor molecules

“…Different from previous studies [15][16][17][18][19] on the interatomic or intermolecular charge transfer and their influences on cluster polarization, we here focus on the intramolecular charge transfer and its influences on molecular polarization. The polarizability partitioning scheme is slightly modified to match the specificity of molecular systems.…”

“…Stone [8,9] developed a general theory of distributed polarizability based on distributed multipole analysis. Ángyán et al [10,11] proposed a scheme to topologically partition electric properties by using Bader's theory of atoms in molecules (AIM) and applied it into the study of intermolecular interaction energies and distributed polarizabilities of homomolecular dimers such as H 2 O and CO. Based on Hirshfeld population analysis [12][13][14], we have reported an alternative polarizability partitioning scheme in our previous studies [15][16][17][18][19]. The total polarizability of atomic or molecular clusters is decomposed into local and charge-transfer parts.…”