Host–Guest Hydrogen Bonding Varies the Charge‐State Behavior of Magnetic Sponges

Abstract

The electron-donor(D) and -acceptor(A)-assembled D 2 A-layer framework [{Ru 2 (m-FPhCO 2 ) 4 } 2 TCNQ-(OMe) 2 ]·nDCE (1-nDCE;m -FPhCO 2 À = m-fluorobenzoate; TCNQ(OMe) 2 = 2,5-dimethoxyl-7,7,8,8-tetracyanoquinodimethane;D CE = 1,2-dichloroethane) undergoes drastic charge-ordered state variations via three distinct states that are atwo-electron-transferred state (2e-I), acharge-disproportionated state (1.5e-I), and aone-electron-transferred state (1e-

A Host–Guest Electron Transfer Mechanism for Magnetic and Electronic Modifications in a Redox‐Active Metal–Organic Framework

“…The magnetization (M) of 1-DCM was collected at different temperatures by applying several dc fields (H dc ) during the cooling process, i.e., field-cooled magnetization (FCM; Figure 3a); profiles of magnetic susceptibility (χ = M/ H dc ) and T product taken at H dc = 1 kOe are given in Figure S5a. The χ T (H dc = 1 kOe) at 300 K was 2.79 cm 3 K mol À 1 , which is higher than the spin-only value of 2.00 cm 3 K mol À 1 expected for two magnetically isolated ] + units are strongly antiferromagnetically coupled with the radical spin of BTDA-TCNQ *À , i.e., growing ferrimagnetically ordered domains at each layer even at 300 K. [10,[15][16][17][18] With decreasing temperature, the χ T product gradually increased and considerably escalated at � 100 K to reach a maximum 101 cm 3 K mol À 1 at 83 K, followed by an abrupt decrease to 0.14 cm 3 K mol À 1 at 1.8 K (Figure S5a). The χ, with a peak at 83 K, is similar to the aforementioned Λ-shaped profile of χ T. This behavior is typical for this type of layered antiferromagnet, i.e., ferrimagnetically ordered layers exhibiting interlayer antiferromagnetic interactions.…”

“…In the class of MOF‐magnets, host–guest interactions have been targeted for tuning bulk magnetism. Currently, the driving force or essential trigger contributed by chemical guests, which can play a versatile role in switchable magnets, can be classified into five cases: i) weak host–guest interactions, e.g., hydrogen bonding and π–π interaction, as electronic perturbations; [5, 7, 17] ii) bond formation/cleavage in frameworks where the guest is strongly associated with the modification of structural dimensions or magnetic pathways; [6, 8, 9, 14] iii) spin coupling with the host framework mediated by paramagnetic guests, such as oxygen; [16] iv) structural modifications involving expansion, shrinkage, rotation, and disorder, as well as the crystalline‐amorphous transformation, apart from the aforementioned case (ii); [10–13, 15, 18] and v) complete charge distribution between the framework and guests, that is, host‐guest electron transfer (HGET). Among these scenarios, the HGET described in scenario (v) affords a crucial trigger that can cause a significant change in magnetism.…”

Chameleonic layered metal–organic frameworks with variable charge-ordered states triggered by temperature and guest molecules

“…[1][2][3] One of the most intriguing targets for SRMMs is a class of thermally driven electron transfer (TDET) systems, which can also be a strong candidate for SRMMs triggered by other external stimuli such as light, 12,14,16,19,20,23,[32][33][34][35] pressure, 6,36 and chemical guests. 26,[37][38][39] Therefore, to date, various types of TDETs, such as neutral-ionic transition (N-I transition), 5,9,18,25,27,38 valence tautomerism (VT), 4,6,8,10,11,21,22,24,28,30,31 and inter-valence electron transfer (IVET), 7,13 have been investigated using organic charge-transfer systems and metal complexes. Most of these systems have been studied using a one-step TDET that occurs at one transition temperature T 1/2 (1) , and only a few examples of two-or multi-step TDET with T 1/2 (1) , T 1/2 (2) , and T 1/2(x) (T 1/2(1) < T 1/2(2) < T 1/2(x) ) have been reported thus far: (i) discrete molecules, where two VT subunits interact electronically with each other, i.e., owing to electronic disproportionation, 10,21,<...>…”

Magnetic Correlation Engineering in Spin‐Sandwiched Layered Magnetic Frameworks

“…In such systems, various types of molecules [21][22][23][24] or ions [25][26][27][28] could be insertedb etween the magnetic layers to result in flexible charge variationsw ithoutc hanging the basic layered framework (Scheme 1a). [29][30][31][32] Among them, p-conjugated inserted molecules were sandwiched between adjacent TCNQ moieties of the layers with a p-stacking mode to form a p-stacked pillared layer framework (p-PLF). [33] On the basis of this type of structuralm ode, an aggressive strategyt owardr ational tuning of the interlayer interaction is to insert ap aramagnetic pillar into the PLF architecture, which could create an anisotropic 3D magnetic pathwayt hrough as upramolecular infinite framework.…”