Synthesis and Properties of Salicylaldehydes Fine-Tuned by Modular Assembly using “Plug-and-Socket”-Type Extendibility

4 years ago

Synthesis and Properties of Salicylaldehydes Fine-Tuned by Modular Assembly using “Plug-and-Socket”-Type Extendibility

Yoshikazu Suzuki, Qian-Wen Shen, Toshiki Mutai, Isao Yoshikawa, Hirohiko Houjou

A salicylaldehyde derivative bearing four pyridine arms, 3,5-bis(N,N-bis(2-pyridylmethyl)aminomethyl)-2,4-dihydroxybenzaldehyde (Hbpsal) as a “socket”, was prepared and used to derive a series of zinc complexes with various extra anions “plugged” into their vacant site. The crystal structure and 1H NMR spectra were noticeably influenced by the extra anions, allowing fine-tuning of the properties by “plug-and-socket”-type modification. Similar to unsubstituted salicylaldehyde, the zinc complexes reacted with primary amines to afford Schiff-base compounds. Because of the potential chirality around the coordination sphere, reaction with a chiral amine resulted in an equilibrium system between diastereomers, the potential of which as chiral sources tunable by the extra anions is discussed. Some of the complexes were further converted into zinc- or nickel-salphen (=N,N-bis(salicylidene)-1,2-phenylenediamine) complexes. The electrochemical properties of the nickel complex were slightly modified by the extra anions, whereas the photophysical properties of the zinc complex appeared unchanged. Peripherals: Salicylaldehyde provided with a “socket”-shaped zinc complex into which various extra anions can be “plugged” was developed. The prochirality around the coordination sphere demonstrated its potential as a chiral source tunable by the extra anions. The salicylaldehyde was derived to Schiff-base complexes, the electrochemistry of which was significantly influenced by the anions.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701141