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The combination of a cobalt-dioxolene core that exhibits valence tautomerism (VT) with pyridine-3,5-dicarboxylic acid functionalized with chains bearing two, four, or six oxyethylene units led to new complexes ConEGEspy (n = 2, 4, and 6). These complexes commonly form violet crystals of the low-spin (ls)-[Co III (nEGEspy) 2 (3,6-DTBSQ)(3,6-DTBCat)] (ls-[Co III ], 3,6-DTBSQ = 3,6-di-tert-butyl semiquinonato, 3,6-DTBCat = 3,6-di-tert-butyl catecholato). Interestingly, violet crystals of Co2EGEspy in the ls-[Co III ] transitioned into a green liquid, accompanied by an almost complete VT shift (94 %) to the high-spin (hs)-[Co II (nEGEspy) 2 (3,6-DTBSQ) 2 ] (hs-[Co II ]) upon melting. In contrast, violet crystals of Co4EGEspy and Co6EGEspy in the ls-[Co III ] exhibited partial VT (33 %) and only a 9.3 % VT shift after melting, respectively. These data demonstrate the tunability of the synchronicity of the molecular VT and macroscopic solid-liquid transitions by optimizing the tethered chains, thus establishing a new strategy for coupling bistable molecules with the macroscopic world., (© 2021 Wiley-VCH GmbH.)

The insertion of "sandwiched spins" between magnetic layers could efficiently affect the interlayer magnetic correlations, but doing so increases the complexity in the interlayer spin alignment because of competition between the inserted spin-layer interaction J NNI and the interlayer through-space interaction J NNNI if the magnitude of J NNI is of the same order as J NNNI with reciprocal signs of the respective interactions. Herein, systematic tuning of the magnetic phase variations by J NNI and J NNNI in two kinds of metal-variable isostructural series of supramolecular pillared layer magnets [MCp* 2 ][{Ru 2 II,II (2,3,5,6-F 4 CO 2 ) 4 } 2 (TCNQ)]⋅2 DCE (M=Co, Fe, Cr; 2,3,5,6-F 4 PhCO 2 - =2,3,5,6-tetrafluorobenzoate; TCNQ=7,7,8,8-tetracyano-p-quinodimethane; DCE=1,2-dichloroethane) and their DCE-free series, in which [MCp* 2 ] + (Cp*=η 5 -C 5 Me 5 ) species with S=0, 1/2, and 3/2 for M=Co, Fe, Cr, respectively, are sandwiched between ferrimagnetic layers of [{Ru 2 } 2 (TCNQ)] - , is demonstrated. The results showed that the flexible magnetic natures of these magnets are changeable in dependence on J NNI and J NNNI , as well as on interlayer inserted spins M., (© 2020 Wiley-VCH GmbH.)

Optimal control of gas adsorption properties in metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) remains a great challenge in the field of materials science. An efficient strategy to capture electron-acceptor-type gas molecules such as nitrogen monooxide (NO) is to use host-guest interactions by utilizing electron-donor-type MOFs/PCPs as host frameworks. Herein, we focus on a highly electron-donating chain compound by using the paddlewheel-type [Ru 2 II,II ] complex [Ru 2 (2,4,5-Me 3 PhCO 2 ) 4 ] (2,4,5-Me 3 PhCO 2 - =2,4,5-trimethylbenzoate) with the phenazine (phz) linker: [Ru 2 (2,4,5-Me 3 PhCO 2 ) 4 (phz)] (1). Compound 1 exhibited a specific gated adsorption for NO under gas pressures greater than 60 kPa at 121 K, which finally resulted in approximately seven molar equivalents being taken up at 100 kPa followed by four molar equivalents remaining under vacuum at 121 K; its Rh isomorph (2) with weaker donation ability was inactive for NO. When the sample of 1⊃4 NO was heated to room temperature, the compound underwent a crystal-to-crystal phase transition to give [Ru 2 (2,4,5-Me 3 PhCO 2 ) 4 (NO) 2 ](phz) (1-NO), involving a post-synthetic nitrosylation on the [Ru 2 ] unit, accompanied by an eventful site-exchange with phz. This drastic event, which is dependent on the NO pressure, temperature, and time, was coherently monitored by using several different in situ techniques, revealing that the stabilization of NO molecules in nanosized pores dynamically and stepwisely occurred with the support of strong electronic/magnetic host-guest interactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Magnetic phase switching in a coordination polymer is reported, which is demonstrated by combining two processes: (A) the pre-organization of magnetic/redox-active molecules into a framework, and (B) a post-treatment through electrochemical tuning of the pre-organized molecules. A TTF .+ -TCNQ .- salt (TTF=tetrathiafulvalene; TCNQ=7,7,8,8-tetracyano-p-quinodimethane) was incorporated into a three-dimensional framework with paddlewheel-type dimetal(II, II) units ([M 2 II,II ]; M=Ru with S=1, 1; and Rh with S=0, 2), where the [M 2 II,II ] and TCNQ .- units form the coordinating framework, and TTF .+ is located in the pores of framework, forming an irregular π-stacking alternating column with the TCNQ .- in the framework. In 1, the spins of [Ru 2 II,II ] and TCNQ .- units make a magnetic correlation through the framework upon decreasing the temperature from 300 K, which is, however, suddenly suppressed below 137 K (=T d (1)) by the formation of a spin singlet in the TTF .+ -TCNQ .- columns, as seen in the spin-Peierls transition (T d (2)=200 K). This material was incorporated as a cathode in a Li-ion battery (LIB); a long-range ferrimagnetic correlation was formed through the three-dimensional [{Ru 2 II,II } 2 TCNQ] - framework at T c =78 K in the discharge process. The reversible magnetic phase switching between the non-volatile ferrimagnetic and paramagnetic states, resulting from the local spin tuning of quasi-spin-Peierls singlet, is demonstrated through the discharge/charge cycling of the LIB., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)