MS36-P25 Structures and physical properties of some derivatives of 2,2';6',2"-terpydine chelating Fe/Co metal complexes I-Jui Hsu (Institute of Organic and Polymeric Materials, Taipei, Taiwan) Yan-An Chen (Institute of Organic and Polymeric Materials, Taipei, Taiwan) Ming-Jing Hsu (Institute of Organic and Polymeric Materials, Taipei, Taiwan) Yu-Chun Chuang (National Synchrotron Radiation Research Center, Hsinchu , Taiwan) Jey-Jau Lee (National Synchrotron Radiation Research Center, Hsinchu, Taiwan) Jyh-Fu Lee (National Synchrotron Radiation Research Center, Hsinchu, Taiwan)email: muti-functional metal complex with magnetic, luminescence, or conductivity properties is one of the directions to design new modern materials. Spin crossover (SCO) compound is one kind of these complexes due to its potential applications to sensors, information storage, cantilever and so on. In this work, we modify terpyridine to 4'-(2-Furyl)-2,2';6',2''-terpyridine (ftpy) and 1-methyl-1H-Pyrrol-2-yl-2,2';6',2''-terpyridine (mtpy), and successfully obtained metal complexes M(II)L2(BF4)2 ( M = Fe(II), Co(II); L = ftpy, mtpy). In these metal complexes, Co(II)(ftpy)2(BF4)21.5H2O (complex 1) exhibits SCO behavior from high spin (HS) state with μ eff = 4.10 B.M. at 350K to low spin (LS) state with μ eff = 2.14 B.M. at 100K, but Co(mtpy)2(BF4)2 (complex 2) only displays HS state. The other Fe(II) complexes both exhibit diamagnetism. To resolve how structure variation leads to the SCO phenomenon so that we can realize why complex 1 exhibits SCO character, the temperature dependent powder x-ray diffraction (PXRD) measurements are carried out at TPS09A beamline and the high resolution PXRD data are analyzed by Rietveld refinement to obtain detailed structural information. The results indicate that the crystal structures are still in triclinic system from 90K (LS) to 350K (HS) with averaged Co-N distance varied from 2.02(3) Å to 2.10(1) Å. Taking insight into crystal packing structure, one H2O is located at ~ 2.41 Å away from one of furan in complex 1, but no solvent molecule in complex 2. This short distance may indicate intermolecular interaction plays a critical role in tuning SCO phenomenon. In addition, the temperature dependent of x-ray absorption spectroscopy (XAS) is applied to study the electronic structures of complex 1. Moreover, the UV absorption and photoluminescence characters of ftpy and mtpy are also discussed in this study.References:

Keywords: PXRD, XAS, spin crossover