The formation mechanism of ZnTPyP fibers fabricated by a surfactant-assisted method

摘要: Fibers composed of 5,10,15,20-tetrakis(4-pyridyl)porphyrinatozinc(II) (ZnTPyP) were synthesized by a surfactant-assisted method using cetyltrimethylammonium bromide (CTAB) and chloroform. The presence CTAB was essential to make maintain the fibers their formation rate became slower with increasing molar ratio ZnTPyP. Measurements absorption spectra showed splitting Soret band at 426 nm into two peaks 416 454 in accordance ZnTPyP as revealed transmission electron microscopy. aging process higher temperature made longer apparent activation energy for estimated be 74.8 kJ mol−1. When 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TPyP) or 5,10,15,20-tetrakis(phenyl)porphyrinatozinc(II) (ZnTPP) used instead ZnTPyP, no fiber observed. On other hand, when chloroform solution ZnTPP mixed pyrazine 4,4′-bipyridine, Proton nuclear magnetic resonance indicated upfield shifts pyridinic proton suggesting coordination nitrogen zinc(II) (Zn–N) ZnTPP. These findings indicate that Zn–N is crucial pyridyl moiety coordinated central ion another molecule fibers. Theoretical calculations performed DFT/B97D functional estimate stability π–π stacking Zn–N. micelles suppresses aggregation molecules due stacking, which thermodynamically more favorable. proceeds moderately during 10 days inducing transition from spherical rod-like fusion.