A repeatable bidirectional paramagnetic ↔ diamagnetic photomagnetic effect has been observed in the cyanide-bridged Fe–Co square complex {[Fe{B(pz)4}(CN)3]2[Co(bik)2]2}(ClO4)2·3H2O [B(pz)4 = tetrapyrazolylborate, bik = bis(1-methylimidazol-2-yl)ketone]. Magnetic measurements and low-temperature single-crystal X-ray diffraction experiments have shown that a complete electron transfer from the diamagnetic FeII −Co III state to the paramagnetic FeIII −Co II metastable state is induced by 808 nm laser light irradiation, whereas the diamagnetic state is recovered in an almost quantitative yield under irradiation at 532 nm.

The self-assembly of [Fe(III)(Tp)(CN)(3)](-) and [Fe(II)(bik)(2)(S)(2)](2+) affords the cyanide-bridged mixed valence {Fe(III)(2)Fe(II)(2)}(2+) molecular square, which exhibits a photomagnetic effect under laser light irradiation at low temperature and also shows thermal spin-state conversion near ambient temperature.

The self-assembly of [Mo(V)(CN)8](3-) and [Fe(II)(bik)2(S)2](2+) affords a cyanide-bridged {Mo(V)2Fe(II)2} rhombus molecule that shows photomagnetic effect under laser light irradiation at low temperature and exhibits thermo-induced spin crossover near ambient temperature.

A cyanide-bridged [Fe 2 Co 2 ] molecular square complex, {[Fe(Tp)(CN) 3 ] 2 [Co(L) 2 ] 2 }(BF 4 ) 2 •2CH 3 CN•6H 2 O [1;Tp = hydrotris(pyrazol-1-yl)borate and L = bis(1-ethyl-1Himidazol-2-yl)ketone], has been synthesized and characterized fully by single-crystal X-ray diffraction, (photo)magnetic measurements, optical reflectivity, and other physical measurements. 1 exhibits a two-step metal-to-metal electron-transfer (MMET)induced spin transition accompanied by thermal hysteresis (T 1/2 ↑ = 332 and 407 K and T 1/2 ↓ = 320 and 405 K, respectively), converting the low-temperature diamagnetic {Fe II LS −CN−Co III LS } ground state into the high-temperature paramagnetic {Fe III LS − CN−Co II HS } state. Additionally, 1 displays reversible photoinduced MMET under light irradiation (ON mode using 808 nm laser light and OFF mode using 532 nm laser light), as confirmed by optical reflectivity and (photo)magnetic measurements. The photoinduced paramagnetic metastable state relaxes back to the diamagnetic ground state at 91 K (T LIESST = 91 K). Astonishingly, 1 also exhibits a 27 K wide light-induced thermal hysteresis below 100 K. The overall results show that 1 is a multistimuli-responsive bistable material that exhibits reversible switching between the diamagnetic state, {Fe II LS −CN−Co III LS }, and the paramagnetic state, {Fe III LS −CN−Co II HS }, under the application of temperature and light.

The iron(II) [2×2] grid complex Fe-8H has been synthesized and characterized. It undergoes spin-crossover (SCO) upon deprotonation of the hydrazine-based terpyridine-like ligand. The deprotonation patterns have been determined by X-ray crystallography and H NMR spectroscopy and discussed in relation to the spin state of the iron(II) centers, which influences greatly the p K of the ligand. The synthesis of the magnetically silent zinc(II) analogue is also reported, and its (de)protonation behavior has been characterized to serve as a reference for the study of the Fe grid complexes. DFT computations have also been performed in order to investigate how the successive deprotonation of the bridging ligands affects the SCO behavior within the grid.

A mononuclear manganese(III) complex containing flexible hexadentate chelating ligand has been prepared and characterised by variable temperature single-crystal X-ray diffraction analyses, magnetic, spectroscopic and electrochemical studies. The complex consists MnN4O2...

A 2D coordination polymer, {[Fe(L) 2 (NCSe) 2 ]•6MeOH•14H 2 O} n (1; L = 2,5-dipyridylethynylene-3,4-ethylenedioxythiophene), has been synthesized based on a redox active luminescence ligand. 1 possesses a 2D [4 × 4] square-grid network where the iron(II) center is in a FeN 6 octahedral coordination environment. 1 displays reversible thermoinduced high-spin (HS; S = 2) to diamagnetic low-spin (LS; S = 0) ON/OFF spin-state switching with a T 1/2 value of 150 K. Interestingly, optical reflectivity and photomagnetic studies at 10 K under light irradiation revealed an efficient conversion to a photoinduced metastable HS excited state from a LS ground state. Remarkably, the photoexcited HS state can be reversibly switched ON and OFF by using 625 and 850 nm light-emitting-diode lights. Intriguingly, the thermal dependence of the luminescence intensity of the maximum emission at 524 nm for 1 shows a minimum at around the spin-crossover (SCO) temperature, indicating a cooperative nature between the SCO and luminescence properties. Theoretical calculations confirmed the above findings.

For the first time, a mononuclear cobalt(ii) complex with dicyanamide coligands exhibiting reversible spin crossover behavior at high temperature is reported.