Six crystalline polyoxo-titanium clusters (PTCs) derived from oximes, namely, Ti4(μ4-O)(OMe)6(L1)4 (PTC-125; H2L1 = salicylaldoxime), H[Ti5(μ2-O)(μ3-O)2(OMe)3(L1)6] (PTC-126), Ti6(μ2-O)(μ3-O)2(OiPr)10(OAc)2(L2)2 (PTC-127; H3L2 = salicylhydroxamic acid; HOAc = acetic acid), Ti7(μ3-O)2(OEt)18(L2)2 (PTC-128), Ti12(μ2-O)4(μ3-O)4(OEt)20(L2)4 (PTC-129), and Ti18(μ2-O)10(μ3-O)8(μ4-O)2(OEt)30(L3)2 (PTC-130; HL3 = acetoxime) have been solvothermally synthesized and structurally characterized. Compared with the reported solid-state monomer, dimer, trimer, and tetramer titanium oximes, these compounds possess high nuclearity structures in the range Ti4, Ti5, Ti6, Ti7, Ti12, and Ti18 as a result of the presence of oxo bridges. Even though three examples of tetranuclear and hexanuclear derivatives have been documented, PTC-130 with a centrosymmetric Ti18 cluster core represents the currently highest PTC compound in the oxime system. In addition, Ti/oximate ratio by solvothermal synthesis in this work possessed a broad range from 0.83:1 to 9:1, different from the constant ratio of 1:1 in the reported ones. According to the solid-state UV–vis diffuse reflectance measurement, the existence of oxime ligands largely enhanced their visible light harvest. Furthermore, their photocurrent response properties are also studied.
Graphical A magneto-fluorescent bifunctional Fe(II) complex is synthesized through decoration of the pyrene fluorophore to Fe(II)-pybox moiety. Its magnetic and fluorescent properties are characterized via X-ray structural analyses, magnetic susceptibility measurement, 57 Fe Mössbauer spectroscopy, and fluorescent spectroscopy. As expected, the coexistence of spin-crossover and fluorescence is achieved. The construction of magneto-fluorescent bifunctional complexes is a feasible approach toward multifunctional molecular materials. Herein we report the synthesis and properties studies of a mononuclear Fe(II) complex [Fe L 2 ](ClO 4 ) ( 1 ), where L is a pyridine-2,6-bis(oxazoline) (pybox) ligand decorated by the pyrene fluorophore. Magnetic susceptibility measurement of desolvated complex 1-d shows an incomplete and gradual spin-crossover in the temperature range 50–300 K, which is further confirmed via 57 Fe Mössbauer spectroscopy study. Light-induced excited spin state trapping (LIESST) is also observed below 70 K when the powder sample is irradiated by a 532 nm laser. The change in absorption during the spin-crossover (SCO) process is investigated via the temperature-dependent UV-vis spectroscopy. As expected, through introducing the chromophore, 1 displays fluorescence in both solution and solid state, achieving the coexistence of spin-crossover and fluorescence in one compound.
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