Permanent Porosity in the Room-Temperature Magnet and Magnonic Material V(TCNE)₂

Abstract

Materials that simultaneously exhibit permanent porosity and high-temperature magnetic order could lead to advances in fundamental physics and numerous emerging technologies. Herein, we show that the archetypal molecule-based magnet and magnonic material V(TCNE)2 (TCNE = tetracyanoethylene) can be desolvated to generate a room-temperature microporous magnet. The solution-phase reaction of V(CO)6 with TCNE yields V(TCNE)2·0.95CH2Cl2, for which a characteristic temperature of T* = 646 K is estimated from a Bloch fit to variable-temperature magnetization data. Removal of the solvent under reduced pressure affords the activated compound V(TCNE)2, which exhibits a T* value of 590 K and permanent microporosity (Langmuir surface area of 850 m2/g). The porous structure of V(TCNE)2 is accessible to the small gas molecules H2, N2, O2, CO2, ethane, and ethylene. While V(TCNE)2 exhibits thermally activated electron transfer with O2, all the other studied gases engage in physisorption. The T* value of V(TCNE)2 is slightly modulated upon adsorption of H2 (T* = 583 K) or CO2 (T* = 596 K), while it decreases more significantly upon ethylene insertion (T* = 459 K). These results provide an initial demonstration of microporosity in a room-temperature magnet and highlight the possibility of further incorporation of small-molecule guests, potentially even molecular qubits, toward future applications.

Optical Phenomena in Molecule-Based Magnetic Materials

“…Molecule-based magnetic materials provide also an efficient molecular platform for the implementation of multifunctionality defined as the presence of a few different physical functionalities in a single-phase system. , Multifunctionality is desired in the pursuit of highly miniaturized advanced devices realizing multiple functions simultaneously and can be achieved by the construction of composite materials built of well-distinguished functional components, e.g., magnetic metal-oxide nanoparticles covered by luminescent quantum dots. − However, it was proved that multifunctionality can be generated at the molecular level using the predesigned molecular building blocks bearing defined physical properties that are bound into the single phase which results in their combination of, e.g., chirality with ferroelectricity, super-ionic conductivity with porosity, electronic conductivity with catalytic activity, etc. − In these regards, various magnetic phenomena were combined with diverse physical functionalities, such as super-ionic and electronic conductivity, , nonlinear optical, luminescent, and chiroptical effects, porosity, pyro-, piezo-, and ferroelectricity, , electrochemical activity, and also others. ,, In some material systems, these properties simply co-exist but they can interact with each other giving new physical cross-effects, such as magneto-chiral dichroism (MChD) being the result of chirality and magnetism in the designed material. ,, The products of multifunctionality are particularly rich when the generated physical effects are combined not only with the magnetic effects but also with the sensitivity to external stimuli leading to multifunctional molecular magnetic switches. − …”

Densely Packed CO2 Aids Charge, Spin, and Lattice Ordering Partially Fluctuated in a Porous Metal–Organic Framework Magnet

“…[12][13][14][15] A family of charge-flexible frameworks composed of electron-donor (D) and -acceptor (A) subunits, referred to as D/A-MOFs, [16,17] is a promising material for guest sensing because the charge states in this type of framework are likely to be sensitive to structural changes caused by guest-inserting and -releasing events, i.e., breathing behavior, owning to charge fluctuations. [18][19][20][21][22][23][24][25][26] The charge fluctuation is due to the transfer of electrons moving from the D-moiety to the A-moiety, resulting in a change of the electron distribution in a D/A-MOF. Considering this feature of D/A-MOFs, the high sensitivity of charge states tuned in D/A-MOFs can sometimes be affected by structural disordering or defects, leading to partial charge fluctuations, which can cause an unpredictable magnetic behavior with an uncertain ordering temperature.…”

Assembly of a trapped valent CeIII/IV–TCNQ complex through metal–ligand redox cooperativity

“…[9][10][11] Electron acceptors such as fullerenes, TCNQ (tetracyanoquinodimethane), TCNE (tetracyanoethylene) and others have been shown to assemble notable structures and associated, collective properties through charge transfer processes. [12][13][14] TCNQ and TCNE offer multiple accessible redox states and four terminal cyano-functionalities that bind metal coordination sites to assemble magnetic, conducting and multifunctional materials. 5,15,16 Mixed valent ferrocene-TCNQ materials comprising p-p interactions have also been assembled by charge transfer processes.…”