Abstract

The crystal and molecular structure of a new polymorph of four-coordinated Zn(II) tetraphenylporphyrin, with formula ZnTPP (TPP = 5,10,15,20-tetraphenyl porphyrin) has been determined from 3D X-ray diffraction data. The new polymorph crystallizes in the tetragonal space group, I4/m with cell dimensions a = 13.4206(9), c = 9.7210(16) Å, V = 1750.9(3) ų, and Z = 4. The previous polymorph was crystallized in triclinic space group, P\(\bar {1}\). The single crystal of toluene solvate, a pseudopolymorph of tetraphenylporphinatozinc(II), ZnTPP ⋅ 2C₇H₈ was also crystallized in the triclinic space group, P\(\bar {1}\). The porphyrin cores of all the three centrosymmetric crystalline forms adopt a planar conformation which is attributed to the equivalent size of Zn²⁺ cations and that of porphyrin cores. In contrast to the two previous triclinic structures, which have two crystallography unique pyrrole rings, the tetragonal structure in the present form has all the pyrrole rings symmetric in nature. Further the symmetric orientations of phenyl rings about the mean N₄ plane in the present form, unlike the two previous triclinic forms in which phenyl rings makes two types of dihedral angles with mean N₄ plane reflects that the tetragonal structure of ZnTPP is the highly ordered geometry. All the four Zn–N bond distances in the present form are equal i.e., 2.048(2) Å and is slightly longer than the average Zn–N bond distances found in the previous triclinic forms. The 3D packing of present form features sandwich type or face to face stacked layers that are bridged by a body centred molecule. The crystal packing is mainly stabilised by C–H⋅⋅⋅C and H⋅⋅⋅H intermolecular forces. Further the role and nature of various intermolecular interactions were quantitatively analysed by 3D Hirschfeld surface analysis and associated 2D fingerprint plots. The optical absorption spectra of ZnTPP and its free base analog, H₂TPP have been further analysed in pure organic solvents of CH₂Cl₂ and CH₃OH at different ionic strengths of the media and their results have been discussed in detail.

中文翻译：

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高对称性四苯基卟啉锌（TPP）Zn的新多晶型物的晶体结构，Hirschfeld表面分析和吸收光谱

摘要

由3D X射线衍射数据确定了四配位的四配位Zn（II）四苯基卟啉的新多晶型物的晶体和分子结构，分子式为Zn TPP（TPP = 5,10,15,20-四苯基卟啉）。新多晶型物结晶的四方晶空间群中，我4 /米与细胞尺寸一个= 13.4206（9），C ^ = 9.7210（16）A，V = 1750.9（3）³，和Ž = 4。以前多晶型物是在三斜空间群P \（\ bar {1} \）中结晶。甲苯溶剂化物的单晶，四苯基卟啉锌（II）的假多晶型物，Zn TPP⋅2C ₇ H ₈也在三斜晶空间群P \（\ bar {1} \）中结晶。三种中心对称晶型的卟啉核均具有平面构象，这归因于Zn ²⁺阳离子和卟啉核的当量大小。与具有两个晶体学独特的吡咯环的先前两个三斜结构相反，本形式的四方结构具有本质上对称的所有吡咯环。此外，在本形式中，苯环围绕平均N ₄平面的对称取向，不同于之前的三斜形式，其中苯环与平均N ₄形成两种类型的二面角平面反映了Zn TPP的四方结构是高度有序的几何形状。当前形式中的所有四个Zn–N键距均相等，即2.048（2）Å，并且比以前的三斜形式中的平均Zn–N键距稍长。当前形式的3D填充物具有三明治式或面对面堆叠的层，这些堆叠层由以人体为中心的分子桥接。晶体堆积主要由C–H⋅⋅⋅C和H⋅⋅⋅H分子间作用力稳定。此外，通过3D Hirschfeld表面分析和相关的2D指纹图谱定量分析了各种分子间相互作用的作用和性质。Zn TPP及其游离碱类似物H ₂ TPP的光吸收光谱在CH ₂ Cl ₂和CH ₃ OH的纯有机溶剂中，在不同离子强度的介质中对它们进行了进一步分析，并对它们的结果进行了详细讨论。