Copper(II) Complexes of salen Analogues with Two Differently Substituted (Push-Pull) Salicylaldehyde Moieties. A Study on the Modulation of Electronic Asymmetry and Nonlinear Optical Properties
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- 作者：Luca Rigamonti ; Francesco Demartin ; Alessandra Forni ; Stefania Righetto ; Alessandro Pasini
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：December 25, 2006
- 年：2006
- 卷：45
- 期：26
- 页码：10976 - 10989
- 全文大小：413K
- 年卷期：v.45,no.26(December 25, 2006)
- ISSN：1520-510X
文摘
This paper presents some copper(II) complexes of salen analogues in which the two salicylaldehyde moieties carrydifferent (electron donor, D, and acceptor, A) substituents in position 5, producing a push-pull charge asymmetry.The X-ray structures of some compounds show the presence of pairs of stacked molecules with head-to-tailintermolecular associations. The geometries of all complexes have been optimized through density functional theory(DFT) studies, which have shown that a major influence on the coordination bond lengths is given by the presenceof the electron acceptor NO2 group. Such an influence operates mainly on the Cu-phenolato bonds: elongationof the Cu-O distance of the 5-nitrosalicylaldehyde moiety, with a concomitant decrease of the other Cu-O distance;the Cu-N bonds are less affected. The D groups have only a minor influence. The nonlinear optical responses,
g
vec, of some molecules have been determined by EFISH measurements, and the vec values have been obtainedusing the DFT-calculated g values because solubility problems hampered the experimental measurements of gof some derivatives; the former, however, have been found to be in agreement with the experimental values thatcould be obtained. Deconvolution of the absorption bands in the near-UV region has allowed recognition of thecharge-transfer (CT) transition, assigned to a ligand-to-metal CT (LMCT) by time-dependent DFT computations;we have then used the solvatochromism of this transition to obtain 0 and CT values using the two-state model.These values were compared with those obtained by computational studies, which have also allowed evaluationof the influence of the substituents on the directions of g and tot.
gvec, of some molecules have been determined by EFISH measurements, and the vec values have been obtainedusing the DFT-calculated g values because solubility problems hampered the experimental measurements of gof some derivatives; the former, however, have been found to be in agreement with the experimental values thatcould be obtained. Deconvolution of the absorption bands in the near-UV region has allowed recognition of thecharge-transfer (CT) transition, assigned to a ligand-to-metal CT (LMCT) by time-dependent DFT computations;we have then used the solvatochromism of this transition to obtain 0 and CT values using the two-state model.These values were compared with those obtained by computational studies, which have also allowed evaluationof the influence of the substituents on the directions of g and tot.