Structural diversities of squarate-based complexes: photocurrent responses and thermochromic behaviours enchanced by viologens

Abstract

Six new squarate-based complexes with 3-D networks, 2-D layers and 0-D clusters have been prepared. 5 and 6 feature the first examples of incorporating squarate with viologens in one lattice, which exhibit not only photocurrent responses but also reversible thermochromisms.

Encapsulating Halometallates into 3-D Lanthanide-Viologen Frameworks: Controllable Emissions, Reversible Thermochromism, Photocurrent Responses, and Electrical Bistability Behaviors

“…Photo/thermochromic properties of viologen-containing hybrids have been widely reported, which originate from the radical interconversion between the monocation radical [V] +• and the dication [V] 2+ in viologen. , In this work, thermochromisms can be expected due to the presence of viologen-like ligand. Thermochromisms of 2 and 4 were selected as examples, as both compounds exhibit thermochromism behaviors (Figure ).…”

“…Lead­(II) and bismuth­(III) halides are the most frequently observed halometallate-base perovskites, whose structural mofits range from 0-D clusters to 3-D networks based on corner-, edge- or face-sharing of MI 6 octahedra. − As far as the choice of host MOF, photoresponsive lanthanide-MOFs are good candidates because of their high sensitivity for external stimuli, − and their functions can be alerted after the encapsulation of halometallates . For example, some electron-deficient organic molecules were incorporated with halometallates to construct donor–acceptor hybrid materials, in which some interesting phenomena such as optical red-shift and effective photo-induced carrier separation can be achieved. − The encapsulation electron-rich halometallates with electron-deficient cationic frameworks will lead to the formation of novel donor–acceptor hybrid materials, which is still in its infancy due to the cation/anion competition. − ,− , Besides, novel photo/electrical properties such as photochromism and photomagnetism have been frequently observed in this kind of hybrid, − which also hint their application in electrical bistability devices . Viologen-like molecules are good photoresponsive species, and more recently, metalloviologen with viologen coordinated to a second metal was emerged because their radical species can be controlled by the metallic centers .…”

Polymeric Terbium(III) Squarate Hydrate as a Luminescent Magnet

“…Squarate, a dianion of 3,4-dihydroxycyclobut-3-ene-1,2-dione (C4O4 2-, abbreviated as sq hereafter; Scheme 1), has two strongly polarized carbonyl groups to gain the stabilization energy of 2π aromaticity [1]. The negative charges are delocalized among four oxygen atoms which can serve as good O donors in coordination chemistry [2][3][4]. Metal sq salts are known to afford polymeric polynuclear complexes due to μ2to μ4-modes of sq ligands.…”

Positional Isomerism Controlled Electronic and Photochromic Properties of Naphthalene Diimide-Based Chlorozincate Hybrids

“…Owing to their outstanding compositional, structural, and functional diversity, photoresponsive organic–inorganic hybrids have received extensive attention and display a high potential for applications in a range of data storage, filters, optical switches, displays, decorations, nonlinear optics materials, and so forth. − Especially, considerable efforts have been devoted to the development of photoresponsive donor–acceptor systems accompanying photochromism, which are largely dependent on an elaborate combination of electron donors and acceptors and rational modulation of electron behaviors. − …”