Decorating Metal Nitrate with a Coplanar Bipyridine Moiety: A Simple and General Method for Fabricating Photochromic Complexes

Abstract

As a significant class of photochromic materials, crystalline hybrid photochromic materials (CHPMs) have attracted widespread attention of researchers because of their possibilities for generating other photoresponsive properties and advantages in understanding the underlying relationship between structure and photoresponsive performance. The predesign of suitable ligands plays a major role in generating desirable CHPMs. Hitherto, most CHPMs have been built from photodeformable or photoresponsive tectons. However, the synthesis of these ligands is usually time‐consuming and expensive, and this greatly restricts their large‐scale preparation and practical application. Therefore, it is necessary to explore new families of CHPMs besides the existing CHPMs. Herein, a simple and general method for constructing CHPMs by decorating metal nitrate with a coplanar bipyridine moiety, namely 1,10‐phenanthroline (phen), is reported. The resulting products exhibit photocoloration in response to Xe‐lamp irradiation. The electron transfer (ET) from the coplanar NO3− species (as π‐electron donors, π‐EDs) to coplanar phen moieties (as π‐electron acceptors, π‐EAs) is responsible for the resulting photochromism. The influence of the coordination environment and central metal ion on the photochromism was also studied. This work demonstrates that the introduction of coplanar organic tectons as π‐EAs to metal nitrates as π‐EDs with the collaboration of ET and coordination‐assembly strategies is a simple and general method to manufacture CHPMs.

Ligand Tailoring and Functional Group Fusion Strategy for Developing Photochromic Compounds: A Case Study for Pyridinedicarboxylic Acid

“…The first is the broadly explored photosensitive ligands containing electron-deficient units such as pyridiniums and naphthalenediimides, which have been fully demonstrated by the related HPMs with diverse photoresponsive performance. − For example, the introduction of electron-deficient methyl viologen as guests or bipyridinium derivatives as ligands into various ED systems gives birth to a series of HPMs with multiple photoresponsive properties. − The second one is the rigid polydentate N-ligands, − acting as EAs to stabilize the charge-separated state. The oxygen-abundant ligands usually act as EDs during the assembly process.…”

“…One of the widely explored ways toward a novel HPM system is the utilization of a phototriggered electron transfer (ET) mechanism. − As a promising platform for functionalized hybrid materials, − the designability of metal–organic complexes (MOCs) provides feasibility for the construction of HPMs driven by ET, in which the chosen ligands usually play the role of electron donors (EDs) and acceptors (EAs). − Considering the availability of ED ligands, the development of newly available ligands containing EA moieties is significant for the exploration of new HPM systems. Hitherto, chemists mainly utilize two categories of ligands to generate MOC-based HPMs.…”

Inserting protonated phenanthroline derivatives into the interchain voids of anionic halometallate units to generate hybrid materials with tunable photochromic performance

“…Considering the classic template role of an organoamine in the yielding of a hybrid halometallate, in this study, we explored bismuth-chloride-phen and its monosubstituted derivative (5-Cl-phen and 5-NH 2 -phen) systems to produce halometallate-based HPMs with a tunable photochromic performance based on the following considerations (Fig. 1): (a) Bi 3+ as a hard acid could easily bond with Cl − as a hard base to form anionic halometallate building units, which need extra cationic species to balance the charge; (b) the coplanar phen and phen-derivatives could act as potential electron-acceptors (EAs) in the presence of suitable electron donors (EDs); [47][48][49][50] (c) the distinct monosubstituted phen-derivatives offer a way to systematically engineer the photochromic performances of the resulting hybrid halometallate (Fig. 2).…”

Luminescent Turn-On/Turn-Off Sensing Properties of a Water-Stable Cobalt-Based Coordination Polymer

“…Huge interest and great importance will continue to be attached to metal–organic coordination polymers (CPs) in the following years because of their fascinating architectures as well as potential applications as multifunctional hybrid materials in photoluminescence, catalysis, magnetism, gas sorption or separation, proton conduction, etc. − Many efforts have been focused on the acquisition of desirable CP materials bearing both attractive structures and properties, thus leading to the new generation of crystal engineering. It is widely acknowledged that the fabrication of CPs is influenced by various factors, including metal centers, coordinative linkers, temperature, solvent, pH value, etc., which make the structures of target products multitudinous and even unpredictable. − Notably, the employment of diverse ligands with different lengths, sizes, types, geometries, and rigidities are still popular and continuously play an essential role in the generation of corresponding functional materials. − Among the diverse coordinated linkers, N-containing molecules such as pyridine, azole, and triazine as well as their derivatives have been commonly used to fabricate attractive CPs, and the famous ZIF (zeolitic imidazolate framework) series and MAFs (metal azolate frameworks) are the representative of such complexes. − Their various coordination fashions together with strong coordination abilities are responsible for the generation of captivating CPs with promising physicochemical properties. Moreover, polycarboxylate molecules bearing diverse coordination modes have been demonstrated to be great coligands for the generation of organic–inorganic hybrid architectures.…”