Tris(rhenium fac-tricarbonyl) Polypyridine Functionalized Cyclotriguaiacylene Ligands with Rich and Varied Emission

Trinuclear rhenium fac-tricarbonyl bromide complexes have been synthesized coordinated to the host ligands tris­(4-[4-methyl-2,2′-bipyridyl]­methyl)­cyclotriguaiacylene (L1), tris­(4-[4-methyl-2,2′-bipyridoyl])­cyclotriguaiacylene (L2), and tris­(4-[2,2′,6′,2″-terpyridyl]­benzyl)­cyclotriguaiacylene (L3). The structure of L1 and complexes [{Re­(CO)3Br}3(L1)] (1) and [{Re­(CO)3Br}3(L3)] (3) have been elucidated through X-ray single-crystal diffraction, with complex 3 crystallizing as a conglomerate. The steady-state luminescent properties and time-resolved fluorescence studies of the complexes have been conducted and revealed an unusual dual-emission phenomenon for complex 2. Complexes 1 and 2 show red-shifted emission wavelengths in comparison with those typical of monometallic Re­(CO)3-bipy-Br complexes, while complex 3 showed an unusual excitation-dependent variation of emission wavelength.本研究合成了与主体配体配位的三核铼面式(fac)-三羰基溴配合物，所用主体配体包括三(4-[4-甲基-2,2'-联吡啶基]甲基)环三藜芦烃(cyclotriguaiacylene, L1)、三(4-[4-甲基-2,2'-联吡啶甲酰基])环三藜芦烃(L2)以及三(4-[2,2',6',2''-三联吡啶基]苄基)环三藜芦烃(L3)。通过X射线单晶衍射解析了配体L1以及配合物[{Re(CO)₃Br}₃(L1)]（1）和[{Re(CO)₃Br}₃(L3)]（3）的晶体结构，其中配合物3以旋光聚集体形式结晶。对上述配合物开展了稳态发光性能与时间分辨荧光研究，结果显示配合物2呈现出异常的双发射现象。相较于经典单金属Re(CO)₃-联吡啶-溴配合物，配合物1和2的发射波长发生红移；而配合物3则表现出发射波长随激发波长变化的异常特性。