Monitoring and analysis of the seed-directed growth of micro-sized hexapod coordination polymers

Multicomponent fluorescent hexapod coordination polymer particles (CPPs) have been synthesized from Zn²⁺ ions and two kinds of fluorescent building blocks (1,4-biphenyldicarboxylic acid, H₂bpdc and N,N′-phenylenebis(salicyclideneimine)dicarboxylic acid, 1). The ultimate size of the final hexapod CPPs depended upon the size of the initially-formed cube CPPs, which acted as the template for growth of the secondary coordination polymers. SEM studies conducted at numerous stages of growth revealed the several interesting intermediates, which give exceptionally strong evidence for the seed-directed formation of the hexapod CPP. Two continuous processes, the initial formation of seed CPPs with a cubic shape and the growth of secondary CPs on the six facets of the cube seeds for the final formation of micro-sized hexapods, were monitored via microscopy. The analyses of the initial and final products also revealed that they had different chemical compositions and so different optical properties. In addition, zinc oxide particles with a maintained hexapod shape have been prepared from the simple calcination of hexapod CPPs.