Wojciechowska Agnieszka, Janczak Jan, Rojek Tomasz, Ashfaq Muhammad, Malik Magdalena, Trzęsowska Natasza, Wysokiński Rafał, Jezierska Julia
Faculty of Chemistry, Wrocław University of Science and Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland.
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wrocław, Poland.
Molecules. 2024 Jun 6;29(11):2709. doi: 10.3390/molecules29112709.
Although the crystals of coordination polymer {[CuCl(O,O'-L-BrTyr)]}n (1) (L-BrTyr = 3,5-dibromo-L-tyrosine) were formed under basic conditions, crystallographic studies revealed that the OH group of the ligand remained protonated. Two adjacent [CuCl(L-BrTyr)] monomers, bridged by the carboxylate group of the ligand in the bidentate bridging mode, are differently oriented to form a polymeric chain; this specific bridging was detected also by FT-IR and EPR spectroscopy. Each Cu(II) ion in polymeric compound 1 is coordinated in the xy plane by the amino nitrogen and carboxyl oxygen of the parent ligand and the oxygen of the carboxyl group from the symmetry related ligand of the adjacent [Cu(L-BrTyr)Cl] monomer, as well as an independent chlorine ion. In addition, the Cu(II) ion in the polymer chain participates in long-distance intermolecular contacts with the oxygen and bromine atoms of the ligands located in the adjacent chains; these intramolecular contacts were also supported by NCI and NBO quantum chemical calculations and Hirshfeld surface analysis. The resulting elongated octahedral geometry based on the [CuCl(L-BrTyr)] monomer has a lower than axial symmetry, which is also reflected in the symmetry of the calculated molecular EPR g tensor. Consequently, the components of the d-d band obtained by analysis of the NIR-VIS-UV spectrum were assigned to the corresponding electronic transitions.
尽管配位聚合物{[CuCl(O,O'-L-BrTyr)]}n (1)（L-BrTyr = 3,5-二溴-L-酪氨酸）的晶体是在碱性条件下形成的，但晶体学研究表明配体的OH基团保持质子化状态。两个相邻的[CuCl(L-BrTyr)]单体通过配体的羧基以双齿桥连模式桥连，它们的取向不同，从而形成聚合物链；这种特定的桥连也通过傅里叶变换红外光谱（FT-IR）和电子顺磁共振光谱（EPR）检测到。聚合物化合物1中的每个Cu(II)离子在xy平面内由母体配体的氨基氮和羧基氧以及来自相邻[Cu(L-BrTyr)Cl]单体的对称相关配体的羧基氧以及一个独立的氯离子配位。此外，聚合物链中的Cu(II)离子与相邻链中配体的氧和溴原子参与长距离分子间接触；这些分子内接触也得到了非共价相互作用（NCI）和自然键轨道（NBO）量子化学计算以及 Hirshfeld 表面分析的支持。基于[CuCl(L-BrTyr)]单体形成的拉长八面体几何结构具有低于轴向的对称性，这也反映在计算得到的分子EPR g张量的对称性上。因此，通过对近红外-可见-紫外光谱分析得到的d-d带的成分被指定为相应的电子跃迁。
