Tri(pyridinyl)pyridine Viologen-Based Kagome Dual Coordination Polymer with Selective Chromic Response to Soft X-ray and Volatile Organic Amines

Abstract

The development of new responsive smart materials has been highly desirable in the recent decade due to growing demand in our daily life, and extended viologen-based coordination polymers are regarded as proper and promising candidates for stimuli-responsive study. A tri(pyridinyl)pyridine viologen-based Kagome dual (kgd) topological coordination polymer, [Mn 3 Cl 4 (tpptb) 2 ]•Cl 2 •(H 2 O) 2 , (tpptb = N,N′,N″-tri(3-carboxybenzyl)-2,4,6-tri(pyridinium-4-yl)pyridine; 1) has been solvothermally synthesized, which can selectively respond to soft X-ray Al−Kα (λ = 8.357 Å) irradiation but not to UV light and hard X-rays of λ < 1.5418 Å at room temperature. Appealingly, 1 is very sensitive and convenient for the visual detection of various volatile amine vapors, especially ethylamine vapors at a low concentration of 100 ppm, and the vapochromic sample can be recovered after exposure in the air at room temperature. The sequence of amines in vapochromism could be rationalized by combined consideration of vapor pressure, the molecular size, and electron-donor ability of various amine molecules as well as the void spaces of 1. In addition, 1 exhibits an obvious hydrochromic transformation upon heating in the air and an anhydrous atmosphere. Combined XPS and EPR confirmed that these physical and chemical stimuli can cause electron transfer from electron-rich groups to quaternary nitrogen atoms of the ligand to generate chargeseparated radicals, leading to soft X-ray-induced photochromic and selective vapochromic behavior of 1. Such behavior indicates that it will become a convenient, recyclable, and practical multifunctional material for chemical and environmental sensing. These results provide an effective avenue for the rational design and synthesis of multifunctional chromic materials for potential use in sensing devices.

Optically actuating ultra-stable radicals in a large π-conjugated ligand constructed photochromic complex

“…However, the ESR signals became much weaker for QDU-12A. The anomalies should be attributed to radical formation, and then the photo-induced stable radicals magnetically coupled with Cu 2+ centers, inducing the weaker ESR signals than the as-prepared QDU-12 samples [35,36]. The radical generation could also be observed in our previous work [37] and other paramagnetic metal contained photochromic complexes, with the confirmation by the variation of ESR spectra during coloration [19,35,36,[38][39][40].…”

Quadruple Photoresponsive Functionality in a Crystalline Hybrid Material: Photochromism, Photomodulated Fluorescence, Magnetism and Nonlinear Optical Properties

“…Recent studies have demonstrated that the hybrid PMs, [13] particular crystalline hybrid PMs (CHPMs), [14] hold promise as inheriting the merits of each constituents. Hitherto, most of CHPMs are supported by photodeformable ligands with examples of diarylethylene‐/azo‐derivatives [15–18] or photoresponsive ligands like pyridinium‐derivatives [19–30] . Besides the CHPMs based on photodeformable or photoresponsive ligands, [15–40] the conjugated N ‐heterocycle moieties as potential electron acceptors (EAs) are also desirable units for yielding CHPMs [41–50] .…”

“…Hitherto, most of CHPMs are supported by photodeformable ligands with examples of diarylethylene-/azo-derivatives [15][16][17][18] or photoresponsive ligands like pyridinium-derivatives. [19][20][21][22][23][24][25][26][27][28][29][30] Besides the CHPMs based on photodeformable or photoresponsive ligands, the conjugated N-heterocycle moieties as potential electron acceptors (EAs) are also desirable units for yielding CHPMs. [41][42][43][44][45][46][47][48][49][50] The assembly of various EAs moieties, electron donors (EDs) species, and metal ions generates assorted CHPMs driven by photoinduced electron-transfer (ET) between EDs and EAs, [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] and the resulting CHPMs feature additional fascinating photoresponsive functionality like photomagnetism, photocurrent, sensor for X-ray, etc.…”

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

“…Hybrid photochromic materials (HPMs) have gained tremendous attention of researchers for their potential applications in various areas and possibilities for generating other photoresponsive functionality [1–9] . The crystalline HPMs (CHPMs) feature intrinsic advantages in elucidating the structure‐dependent photoswitchable properties, which has received sustained interest of researchers and been broadly investigated [10] .…”

“…The crystalline HPMs (CHPMs) feature intrinsic advantages in elucidating the structure‐dependent photoswitchable properties, which has received sustained interest of researchers and been broadly investigated [10] . Although representative results have been obtained during the development of CHPMs, [2–15] the fabrication of CHPMs with tailor‐made photoresponsive performance is still a challenge to chemists.…”