PMMA matrix viscosity dependence of CD bands of flexible chiral Schiff base Ni(II), Cu(II), and Zn(II) complexes

Abstract

Three chiral Schiff base (bis(N-R-2-phenylpropyl-3,5-dichlorosalicydenaminato)) nickel(II), copper(II), and zinc(II) complexes have been investigated by means of electronic and CD (circular dichroism) spectra is the solid state as well as PMMA solutions of various concentration. Because these complexes possess long and flexible pendant groups, they are sensitive to viscosity of matrix environment. Indeed so-called solid state (artifact) CD peaks could be observed as characteristic to oriented molecules without free molecular rotation and they indicated changes of intensity depending on matrix environment (not concentration but viscosity). For the first time, we have employed chiral metal complexes indicating conformational changes and found that solid state CD peaks can be affected by not only environmental viscosity of a softmater matrix but also structural and spectral features of chiral materials.

Linearly, circularly, or non-polarized light induced supramolecular arrangement of diastereomer Schiff base Ni (II), Cu (II), and Zn (II) complexes by azobenzene in PMMA matrix

“…To measure molecular orientation [12][13][14] or supramolecular chirality [15][16][17], there are some problems about spectroscopy, namely artifact CD peaks in the solid state [18][19][20][21]. In previous paper [22], we have attempted to discuss its effect in view of viscosity of soft-matter matrix and separate real CD peaks. In this way, technical preparation for supramolecular (helical) molecular orientation induced by circularly polarized UV light has been established.…”

Polarized UV light induced molecular arrangement depending on flexibility of chiral Schiff Base Ni(II), Cu(II), and Zn(II) complexes by Azobenzene in PMMA matrix

“…Some instruments have been developed to overcome this problem [7,8]. Recently, we have attempted to discuss its effect in view of viscosity of softmater matrix [9,10] and separate real CD peaks [11]. In this way, technical preparation for supramolecular (helical) molecular orientation induced by circularly polarized UV light has been established and ready at present.…”

The Viscosity and Intermolecular Interaction of Organic and Inorganic Hybrid Systems Composed of Chiral Schiff Base Ni(II), Cu(II), and Zn(II) Complexes with Long Ligands, Azobenzene, and PMMA

“…Our previous studies [19,20] have successfully elucidated that there is a good correlation between viscosity (namely, concentration of PMMA acetone solutions of stiff chiral metal complexes [21]) and intensity of artifact CD peaks, accompanying a gradual restriction of free rotation and losing isotropy of a chiral complex ( Figure S4). In principle, isotropy of a chiral material reduces artifact peaks of CD spectra.…”