Modulating the structure and photochromic performance of hybrid metal chlorides with nonphotochromic 1,10-phenanthroline and its derivative

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 5; no. 48; pp. 1889 - 1896
• Main Authors: Xu, Fei, Li, Gang-Mei, Wang, A-Ni, Han, Song-De, Pan, Jie, Wang, Guo-Ming
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 14.12.2021
• Subjects: Chloride ions; Coordination compounds; Crystal structure; Crystallinity; Electron transfer; Electrons; Lead chlorides; Ligands; Metal chlorides; Metallurgical constituents; Photochromism; Photosensitivity; Synthesis; Zinc chloride
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d1dt02899e

Hybrid photochromic materias (HPMs), especially crystalline HPMs (CHPMs), have been widely investigated due to their feasibility in maintaining the advantages of each constituent and genearating captivating photomodulated functionality. Metal-organic complexes (MOCs), as promising candidates for fabricating CHPMs, have attracted the interest of researchers. The molecular predesign of ligands plays a crucial role in yielding MOC-based CHPMs with tunable photochromic functionality. Hitherto, a great majority of CHPMs are driven by photosensitive ligands. However, the complicated synthesis and high cost of photosensitive ligands obviously prevent the macro-synthesis and future application of these CHPMs. Thus, it is indispensable to explore novel branches of CHPMs. Herein, we report a series of photochromic solid materials bearing modulated photochromic properties by hybridizing metal chlorides with a nonphotosensitive coplanar dipyridine unit 1,10-phenanthroline (phen) and its derivative 5-chloro-1,10-phenanthroline (5-Cl-phen). The resulting hybrids, [ZnCl 2 (phen)] ( 1 ), [CdCl 2 (phen)] ( 2 ), [PbCl 2 (phen)] ( 3 ), [ZnCl(H 2 O)(5-Cl-phen) 2 ]Cl·2H 2 O ( 4 ), [Cd 2 Cl 4 (5-Cl-phen) 2 ] ( 5 ) and [Pb 2 Cl 4 (5-Cl-phen) 2 ] ( 6 ), exhibit distinct structures from the isolated molecular complexes ( 1 and 4 ) to the hybrid chain ( 2 , 3 , 5 and 6 ) because of the distinct coordination mode of central metal ions and chloride ions. After photo-irradiation with a Xe-lamp, all complexes, as expected, exhibited apparent color change because of the photoinduced electron transfer (ET) between coordinated chloride ions (Cl − ) as electron donors (EDs) and the coordinated coplanar phen and 5-Cl-phen species as electron acceptors (EAs). More importantly, the photochromic performance of the title complexes could be modulated by phen and 5-Cl-phen. This study provides a general and facile way for modulating the structure and photochromic performance of hybrid metal chlorides with phen or phen-based derivatives under the synergy of crystalline engineering strategy and ET mechanism. We provide a general method for modulating the structure and photochromic performance of hybrid metal chlorides with 1,10-phenanthroline and its substituted derivative under the synergy of electron transfer and coordination assembly strategies.