Preparation and Electronic Property Investigation of Zinc(II)-Schiff Base Complexes in the Confined Space

Peng Shang,Lei Zhang

doi:10.1155/2013/206847

Abstract

Metal-Schiff base complexes have attracted continued research interest regarding their intriguing and useful features, while the electronic properties of these complexes in the confined space have not been sufficiently addressed in previous studies. In this work, a new zinc(II)-Schiff base complex bis(N-dodecyl salicylideneiminato)Zn(II) (1) was synthesized and subsequently loaded in an inorganic solid host. A large red shift (~40 nm) of the absorption onset was recorded, when the microenvironment of1changed from the solvent ethanol to the inorganic solid medium, evidencing the confined space effect. The marked shift of the absorption onset was associated with a band-gap reduction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Theoretical calculation results showed that the confined space effect is distance dependent and exerts a more profound influence on the HOMO than the LUMO within an effective distance range. An initial study implied that the confined space effect is also accompanied with the electron density variation.

Highlights

Schiff bases, named after Hugo Schiff, have gained immense popularity in the chemical community as a result of their attractive properties and diverse applicability [1,2,3,4,5]
The Zn(II) ion is four-coordinated, and the coordination sphere of the Zn(II) ion is best described as a distorted tetrahedral geometry completed by two oxygen atoms and two nitrogen atoms from the Schiff base ligands. 1 belongs to a C2 point group, where the C2 axis passes through the Zn(II) ion and the midpoint of two nitrogen atoms
Huo and colleagues recently synthesized Zn2 (2), a zinc(II)-Schiff base complex that crystallizes in the monoclinic space group C2/c [22]

Summary

Introduction

Schiff bases, named after Hugo Schiff, have gained immense popularity in the chemical community as a result of their attractive properties and diverse applicability [1,2,3,4,5]. When an organic molecule is placed as a guest inside a host material, its physical and chemical properties are subject to changes, among others due to the so-called “confined space effect” [11]. Pioneered by the work on loading the conducting polyaniline filaments in a mesoporous channel host [12], organic molecules in the confined space have attracted considerable research interest [13,14,15]. Kitayama and colleagues experimentally demonstrated the beneficial use of the confined space effect in the nitroxidemediated radical microemulsion polymerization [16]. It is discovered that combining the merits of the confined space effect and the synergic effect represents a promising way to construct versatile and efficient catalytic systems [17]

Methods

Results

Conclusion