Novel photoluminescent hemi-disclike liquid crystalline Zn(II) complexes of [N2O2] donor 4-alkoxy substituted salicyldimine Schiff base with aromatic spacer

作者：Bhattacharjee Chira R^*; Das Gobinda; Mondal Paritosh; Rao N V S

来源：Polyhedron, 2010, 29(16): 3089-3096.

DOI：10.1016/j.poly.2010.08.017

• Zinc
• Schiff base
• Metallomesogen
• DFT
• Fluorescence

A series of novel hemi-disclike four coordinated distorted square planar Zn(II) Schiff base complexes containing 4-substituted alkoxy chains on the side aromatic ring [Zn (4-CnH2n+1O)(2) salophenl, n = 14, 16, 18 and salophen = N,N'-4-methyl phenylene bis (salicylideneiminato), have been prepared and their mesogenic, photophysical properties were investigated. The phase behavior of these compounds were characterized by differential scanning calorimetry, polarized optical microscopy and variable temperature PXRD study. The ligands are non-mesogenic but the complexes exhibited an unprecedented 2D-hexagonal columnar mesophase (Col(h)) in the temperature 175-185 degrees C range. In the mesophase (Col(h)), the molecules self assemble in a columnar stack in antiparallel fashion. All lambda(max) of the UV-Vis absorption and photoluminescence band occurred at ca. 291-425 and 504-524 nm, respectively. The ligands are non-emissive, but on coordination with Zn(II), the complexes show intense green emission at room temperature in dichloromethane solution (similar to 505 nm, Phi = 20%) as well as in solid (similar to 522 nm, Phi = 9%) at 360 nm excitation. The DFT calculations were performed using D(MOL)3 program at BLYP/DNP level to obtain the stable electronic structure of the complex. A small LUMO-HOMO band gap (similar to 2.1 eV), presumably suggests a rather strong electronic correlation among the molecules along the column.

• 出版日期2010-10-29