Steric Control over Supramolecular Polymer Formation in trans-1,2-Bis(4-pyridyl)ethylene Adducts of Zinc Xanthates: Implications for Luminescence

• Published in: Crystal growth & design 2010-03, Vol.10 (3), p.1247-1256
• Main Authors: Kang, Jun-Gill, Shin, Jung-Sik, Cho, Dong-Hee, Jeong, Yong-Kwang, Park, Changmoon, Soh, Shu Fang, Lai, Chian Sing, Tiekink, Edward R. T
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg9012735

Steric control over supramolecular aggregation is demonstrated for a series of adducts formed between Zn(S2COR)2 and trans-1,2-bis(4-pyridyl)ethylene, whereby supramolecular zigzag polymers are found when R is small, that is, Et (1) and n-Bu (2), but only bimetallic aggregates could be formed when R = Cy (3). This results in different coordination geometries: four-coordinate N2S2 zinc in 1 and 2, and five-coordinate NS4 zinc in 3, a feature which greatly influences photophysical responses in the solid state. When excited in the UV region, {Zn(S2COEt)2L}∞ (1) and {[Zn(S2COCy)2]2L} (3) produce broad luminescence in the visible region. Five-coordinate 3 produces more broad and intense luminescence than four-coordinate 1. The configuration interaction singles (CIS) and post-Hartree−Fock (HF) calculations for 1 and 3 indicate the A-band excited state is responsible for the observed luminescence which is strongly associated with charge transfer from S and Zn.