Anion-dependent crystallization of zinc complexes with the ligand 4′,5′-diaza-9′-(4,5-disubstituted-1,3-dithiol-2-ylidene) fluorene: Structures and spectroscopic properties

Abstract

A series of zinc(II) complexes (1-6) with the ligands 4 0 ,5 0 -diaza-9 0 -(4,5-bis(methylthio)-1,3-dithiol-2ylidene) fluorene (L 1 ) or 4 0 ,5 0 -diaza-9 0 -(4,5-bis(ethylthio)-1,3-dithiol-2-ylidene) fluorene (L 2 ) have been prepared in the presence of different zinc(II) salts, 5), and [Zn(L 2 ) 2 (ClO 4 ) 2 ] (6). Five of the complexes (1-3, 5, and 6) have been structurally characterized by single-crystal X-ray diffraction. The preferred coordination geometry of the zinc(II) center is related to the coordinated anions. Complexes 1, 2 and 6 with oxo-anions display distorted octahedral geometry, while complexes 3 and 5 with chloride anions take five-and four-coordination geometries. The weak coordinated perchlorate anion prefers a trans structure, while the strong coordinated nitrate anion favors a cis structure. The intermolecular C/C, C/S, and S/S interactions lead to the assembly of the complexes into different supramolecular frameworks. The results of the 1 H NMR, UV-vis, and fluorescent spectra display a large effect of metal coordination on the electron density of the ligand. Spectral data for the complexes is in agreement with the crystal structures. Finally, semi-empirical PM3 calculations were carried out to explain the relationship of the structures and the spectra.

Metal–Organic Framework-Inspired Metal-Containing Clusters for High-Resolution Patterning

“…Normally, ZnO nanoparticles have a broad size distribution because of the imprecision of the hydrolysis reaction of either their sol–gel reactions, − microemulsion process, − or hydrothermal reactions. − For Zn-based clusters synthesized by typical cluster formation methods, − the size of individual components can be well-controlled; however, the products are generally obtained as a crystalline material. From the Zn-BA cluster example demonstrated in this work, the individual cluster is small and monodisperse in size, but its crystalline nature leads to crystallites that are problematic in film fabrication and high-resolution patterning.…”

Allosteric Regulation of the Rotational Speed in a Light-Driven Molecular Motor

“…25 The input geometries for DFT energy minimization were adapted as such, and the obtained molecular structures and relative Δ G values are presented in Figure 1.…”

“…The metal-to-nitrogen bond lengths and diazafluorenyl bite angles in the DFT optimized complexes of stable L1 closely resemble those found in the crystal structures of related metal–ligand complexes. 24,25 The M–N bond lengths in the calculated zinc, palladium, and platinum complexes of the stable ligand are about 2.19, 2.09, and 2.07 Å, respectively (cf. 2.13, 2.08, and 2.06 Å in the reported solid state structures of 4,5-diazafluorene complexes).…”

“…2.13, 2.08, and 2.06 Å in the reported solid state structures of 4,5-diazafluorene complexes). 24,25 In addition, the observed diazafluorenyl N–M–N bite angles range from 83.2° for zinc and 84.0° for palladium to 83.6° for platinum (cf. 84.8°, 83.7°, and 83.6° in the solid state structures).…”

“…In the earlier reported X-ray crystal structures of palladium and platinum 4,5-diazafluoren-9-one dichloride complexes, a square planar coordination geometry was observed, whereas the zinc dichloride complex of a structurally related 4,5-diazafluorene derivative revealed a tetrahedral coordination environment . The input geometries for DFT energy minimization were adapted as such, and the obtained molecular structures and relative Δ G values are presented in Figure .…”