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Herein, we report a twisted cubic Cu(I)4Ti(IV)4-oxo cluster stabilized by in situ – formed 2,2′-biphenolate ligands from the oxidative coupling of phenols. The 2,2′-biphenolate-functionalized Cu(I)4Ti(IV)4O4 cluster shows short Cu⋯C contacts and exhibits smaller HOMO–LUMO gaps than those of reported Ti(IV)4O4. [ABSTRACT FROM AUTHOR]

A tetradentate ligand, 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene (TPPE), was adopted to construct a two-dimensional coordination polymer that incorporated valence tautomerism and luminescence, and the synergistic effect arising from energy transfer from TPPE to the semiquinone moieties was experimentally and theoretically uncovered. [ABSTRACT FROM AUTHOR]

Spin-crossover (SCO) materials have been extensively investigated in the past few decades with promising applications in a wide range of fields including displays, sensors, and storage components. The introduction of secondary physical properties to SCO materials resulting in bifunctional materials is becoming a research hot spot. In particular, for the fluorescent SCO materials, fluorescence can serve as a sensitive probe that easily expresses the spin-state changes of SCO materials; therefore, fluorescent SCO bifunctional materials have promising applications in the fields of magneto-optical switching and information processing. In this perspective, we briefly review the main synthetic strategies and progresses in fluorescent SCO materials in the last twenty years. [ABSTRACT FROM AUTHOR]

We report a phosphine-directed ruthenium-catalyzed C8-selective alkylation of naphthalenes with alkenes. This protocol provides straightforward access to a large library of electron-rich C8-alkyl substituent 1-naphthphosphines, which outperformed common commercial phosphines and their precursors in the Pd-catalyzed Suzuki–Miyaura coupling of aryl bromides with alkylboronic acid. [ABSTRACT FROM AUTHOR]

A series of dynamic single crystals with a chemical formula of [MII(en)3]SO4 (en = ethylene and MII = NiII, MnII, and CdII) was synthesized. As the temperature decreases, these materials exhibit dielectric switching in the vicinity of the phase transition point accompanied by anisotropic thermal expansion in the cell parameters as a consequence of the order–disorder structural change of SO 2−4 in a cavity surrounded by five [MII(en)3]2+ complex cations. Because the variation of metal centers with different ionic radii changes the shape of the complex cation, which affects the distribution of hydrogen-bond interactions around the SO 2−4 , the dynamic motion of SO 2−4 is substantially tuned. Correspondingly, the dielectric properties and anisotropic thermal expansion of materials were largely shifted, especially in the single crystals of [MnII(en)3]SO4, whose structural change is distinctly different from the crystals of Ni(II) and Cd(II). The detailed structural mechanism accounting for the different physical properties of these materials was discussed. [ABSTRACT FROM AUTHOR]

Further towards the fast, continuous, efficient and scaled-up production of energetic cocrystals, a microchannel-confined crystallization strategy has been developed to prepare a high-quality CL-20/HMX cocrystal with desired shape and size. Applying the flow-focusing microchannel, the mixing efficiency of solution and antisolvent and supersaturation were facilely regulated through changing the solution concentration and flow rate ratio of the solution and antisolvent. At the solution concentration of 0.25 mol L−1 and flow rate ratio of 1 : 6, a pure CL-20/HMX cocrystal with a cube-shaped appearance and a particle diameter D (4, 3) of 21.8 μm has been obtained, overcoming the problem easy to crystallize in platelet morphology. This cocrystal presents a sharp decomposition within a very narrow temperature range (245.1 °C to 246.2 °C) and a peak temperature of 245.4 °C, close to that of raw CL-20, showing a quick energy release rate. TG-FTIR and thermal analysis illustrate that its thermal behavior under isothermal conditions is determined by the decomposition of the least stable CL-20 molecules. A high density of 1.9552 ± 0.0014 g cm−3 at room temperature, few internal defects and friction impact sensitivity, even lower than that of raw HMX, mean high crystal quality of the CL-20/HMX cocrystal. [ABSTRACT FROM AUTHOR]

A mononuclear complex with long alkyl chains, [FeII(H2Bpz2)2(C9bpy)] (1; H2Bpz2 = dihydrobis(1-pyrazolyl)borate, C9bpy = 4,4′-dinonyl-2,2′-bipyridine), was synthesized. Single-crystal X-ray crystallographic studies revealed that the Δ- and Λ-forms of the complex co-crystallized in the lattice asymmetric unit, while magnetic measurements unveiled that this complex underwent incomplete one-step spin crossover (SCO) with the transition completeness and temperature depending on the measurement velocity because of slow spin equilibrium. Multivariable approaches such as varying scan rate, annealing the sample, light irradiation and pressure have been adopted to effectively overcome the slow spin equilibrium and thus improve the SCO completeness. [ABSTRACT FROM AUTHOR]

Controlled electrical stimulation is essential for evaluating the physiology of cardiac tissues engineered in heart-on-a-chip devices. However, existing stimulation techniques, such as external platinum electrodes or opaque microelectrode arrays patterned on glass substrates, have limited throughput, reproducibility, or compatibility with other desirable features of heart-on-a-chip systems, such as the use of tunable culture substrates, imaging accessibility, or enclosure in a microfluidic device. In this study, indium tin oxide (ITO), a conductive, semi-transparent, and biocompatible material, was deposited onto glass and polydimethylsiloxane (PDMS)-coated coverslips as parallel or point stimulation electrodes using laser-cut tape masks. ITO caused substrate discoloration but did not prevent brightfield imaging. ITO-patterned substrates were microcontact printed with arrayed lines of fibronectin and seeded with neonatal rat ventricular myocytes, which assembled into aligned cardiac tissues. ITO deposited as parallel or point electrodes was connected to an external stimulator and used to successfully stimulate micropatterned cardiac tissues to generate calcium transients or propagating calcium waves, respectively. ITO electrodes were also integrated into the cantilever-based muscular thin film (MTF) assay to stimulate and quantify the contraction of micropatterned cardiac tissues. To demonstrate the potential for multiple ITO electrodes to be integrated into larger, multiplexed systems, two sets of ITO electrodes were deposited onto a single substrate and used to stimulate the contraction of distinct micropatterned cardiac tissues independently. Collectively, these approaches for integrating ITO electrodes into heart-on-a-chip devices are relatively facile, modular, and scalable and could have diverse applications in microphysiological systems of excitable tissues. [ABSTRACT FROM AUTHOR]

Hofmann-type spin-crossover (SCO) frameworks attract much attention due to their predictable structures and diverse SCO behaviours. In this paper, we report two isostructural two-dimensional (2D) Hofmann-type SCO frameworks [FeII(ppe)2MII(CN)4]·3H2O (ppe = 1-(2-pyridyl)-2-(4-pyridyl)ethylene and M = Pd for 1 and Pt for 2). X-ray crystallographic studies, magnetic measurements and Mössbauer spectra jointly reveal that both compounds undergo complete hysteretic two-step SCO, i.e. HS1.0 HS0.6–0.5LS0.4–0.5 LS1.0 conversion with thermal hysteresis loops of 14 K and 28 K wide for 1 and 13 K and 26 K wide for 2. The dehydrated samples, 1-dehydrated and 2-dehydrated, display different SCO behaviours, unveiling that the SCO behaviours are affected by guest water molecules. [ABSTRACT FROM AUTHOR]

The development of molecular materials whose physical properties can be switched between different states has attracted significant attention for their potential application in sensing, information processing, spintronics, and smart actuators. Generally speaking, such functional bistability can be induced by the motion of electrons or constituted molecules in response to external stimuli. In this Feature Article, we will introduce how to manipulate the structural variations, including spin crossover, molecular reorientation, and molecular displacement, to tune the magnetic properties, optical properties, dielectric properties, and mechanical response of single-crystal materials, with a highlight of our contributions to this booming field. [ABSTRACT FROM AUTHOR]

Reversible single crystal-to-single crystal transformations from [FeL2(NCS)2]·3MeOH (1·3MeOH, L = 2-(anthracen-10-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) to 1 and 1·2H2O were reported, which were accompanied by on–off switching of the spin-crossover properties. [ABSTRACT FROM AUTHOR]

An atypical homochiral spin-crossover (SCO) framework (1) constructed from mechanically interlocked 1D molecular loops was prepared. Due to the flexibility of the interlocked structure, the guest solvent molecules can be reversibly exchanged. Consequently, its SCO behavior was capable of modulating between one- and two-stepped transitions in response to acetonitrile and methanol. [ABSTRACT FROM AUTHOR]

Correction for 'Multiple correlations between spin crossover and fluorescence in a dinuclear compound' by Chun-Feng Wang et al., Chem. Commun., 2016, 52, 14322–14325, https://doi.org/10.1039/C6CC07810A. [ABSTRACT FROM AUTHOR]

Three one-dimensional looped coordination polymers with the formula of [Fe(dpds)2{C(CN)3}2]·dpds (1, dpds = 4,4′-dipyridyl disulfide), [Fe(dpds)2(NCBH3)2] (2) and [Fe(dpds)2(NCSe)2]·3.5H2O (3) have been synthesized and characterized by single-crystal X-ray crystallography, Mössbauer spectroscopy and magnetic measurements. The spin-crossover (SCO) behaviors of these compounds depend significantly on axial ligands: compound 1 exhibited thermal-induced complete one-step SCO behavior with a T1/2 of 170 K, and 2 showed incomplete SCO behavior with T1/2 being 130 K, whereas 3 was paramagnetic. Meanwhile, both compounds 1 and 2 displayed light-induced excited spin-state trapping (LIESST) effects, featuring TLIESST values of 45 K and 61 K for 1 and 2, respectively, which were independent of exciting laser wavelengths. These results suggest that anions such as C(CN)3− and NCBH3− with much stronger ligand fields are needed in order to realize spin-state switching, if a ligand such as dpds is adopted to synthesize SCO compounds. [ABSTRACT FROM AUTHOR]

A pair of novel chiral one-dimensional compounds with the general formula [Cd(NO3)2L2]·THF (where L is R- or S-2,2′-bis(methoxymethoxy)-6,6′-bis(4-pyridyl)-1,1′-binaphthyl) for the first time show circularly polarized luminescence, two-photon excited fluorescence, and second harmonic generation activity. [ABSTRACT FROM AUTHOR]

Six analogous dumbbell-shaped 3d–4f complexes MII5LnIII4 were obtained by the reaction of Ln(NO3)3 (Ln = Eu, Gd, Dy) and M(OAc)2 (M = Co, Ni) without any other organic ligands, and M5Gd4 exhibited a large magnetocaloric effect (−ΔSm = 31.0, 37.3 J kg−1 K−1 for Co5Gd4 and Ni5Gd4 respectively), while M5Dy4 and Co5Eu4 showed single molecule magnet behaviour. To the best of our knowledge, Co5Eu4 is the first Eu-based cluster to display single molecule magnet behaviour (Ueff = 16.4 K). [ABSTRACT FROM AUTHOR]

A novel bent ligand-pillared three-dimensional Hofmann-type metal–organic framework, [FeII(Hbpt)Pt(CN)4]·1/2Hbpt·1/2CH3OH·5/2H2O [1, Hbpt = 4,4′-(1H-1,2,4-triazole-3,5-diyl) dipyridine], was synthesized and crystallographically and magnetically characterized, which showed incomplete three-step spin-crossover behavior with a reversible three equal-step sequence of HS1.00↑ HS0.75LS0.25↑ HS0.5LS0.5↑ HS0.25LS0.75. [ABSTRACT FROM AUTHOR]

Mesoporous organosilica nanoparticles (MONs) have attracted increasing interest for guest molecule delivery. In this work, we prepared MONs with radially oriented large pores for the first time in a water–ethanol/n-hexane biphasic reaction system. The MONs possess ethane-incorporated organosilica frameworks, large radial pores with openings of 17–78 nm, a high surface area (1219 cm2 g−1), a large pore volume (2.2 cm3 g−1), tunable diameters (124–287 nm), and excellent biocompatibility. We reveal that the formation of large pore MONs in the biphasic reaction system undergoes a surfactant-directed self-assembly following mesostructure reconstruction, providing a new mechanism for the preparation of large mesoporous nanoparticles. Also, the effects of the reaction parameters including temperature and the stirring rate on the pore size are systemically investigated. Furthermore, large pore MONs were loaded with bovine serum albumin (BSA) and small interference RNA (siRNA), which exhibit high protein loading and siRNA delivery capabilities, suggesting the potential of the MONs for biomedical applications. [ABSTRACT FROM AUTHOR]

The respiratory chain succinate–ubiquinone oxidoreductase (SQR or complex II) is a promising target for fungicide discovery. As a continuation of our research work on the development of new fungicides, a series of bitriazolyl compounds were designed and synthesized in excellent yields by an ionic liquid promoted 1,3-dipolar Huisgen cycloaddition reaction of azides and akynes. These newly synthesized compounds were characterized by 1H NMR, 13C NMR and HR-MS spectroscopy. The in vitro assay indicated that several compounds displayed good inhibitory effects against porcine succinate–cyctochrome reductase (SCR) with IC50 values ranging from 2.89 to 61.19 μM. Compound 1b with an IC50 value of 2.89 μM, comparable to the commercial control penthiopyrad, was identified as the most promising inhibitor. Further evaluation of the representative compounds against respective SQR and cyt bc1 indicated that their inhibitory potency against SQR was much higher than that against cyt bc1, suggesting that SQR might be a potential target of these inhibitors. Furthermore, molecular docking studies suggested that strong hydrogen bonding and π–π stacking interactions might be responsible for a higher SQR inhibitory effect of compound 1b as compared to that of compounds 1d and 2b. Consequently, bitriazolyl compounds, a totally new skeleton that is distinct from the existing commercial SQR-inhibiting fungicides, were discovered, which could potentially be a new lead for further development of SQR inhibitors. [ABSTRACT FROM AUTHOR]

Multiple correlations between spin crossover and fluorescence are established in a dinuclear compound with fluorescence from d(Fe) + π(SCN) to π*(ligand) charge transfer and correlation originated from ligand to Fe(ii) energy transfer. [ABSTRACT FROM AUTHOR]

The reactions of tricyanometallate precursors, (Ph3PMe)[(Tp4-Me)Fe(CN)3·0.5CH3CN] (1) (Tp4-Me = tri(4-methyl-pyrazol-1-yl)borate) and (NBu4)[(MeTp)Fe(CN)3] (MeTp = methyltris(pyrazolyl)borate) with the presence of the tetradentate tpa ligand (tpa = tris(2-pyridylmethyl)amine) and Fe(ClO4)2·6H2O afford two new cyano-bridged mixed-valence {FeIII2FeII2} molecular squares: [(Tp4-Me)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·H2O (2·H2O) and [(MeTp)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·CH3OH (3·CH3OH). Solvent-exchange compounds of 3·CH3OH, [(MeTp)FeIII(CN)3]2[FeII(tpa)]2·2ClO4·2H2O (3·2H2O), and their solvent-free form (2 and 3) are also obtained, respectively. The spin crossover (SCO) properties of all compounds are confirmed by detailed structural analyses of the coordination environments of the FeII centres and magnetic susceptibility measurements. All compounds exhibit SCO behaviour near room temperature (T1/2 = 320 K for 2·H2O; 302 K for 2; 292 K for 3·CH3OH; 306 K for 3·2H2O and 290 K for 3) and reversible single-crystal to single-crystal (SC–SC) transformations induced by guest desorption and resorption or solvent exchange. The transition temperature close to room temperature can be tuned by the dehydration and re-hydration processes. The structure–property analysis discloses that the distorted {Fe4(μ-CN)4} core and deviations of bent 〈Fe−N≡C angles play a key role in tuning the transition temperature of these similar mixed-valence {FeIII2FeII2} complexes. [ABSTRACT FROM AUTHOR]

Two distinct template mediated coordination polymers, [Co3(ina)4(N3)2(CH3OH)2] with tri-nuclear nodes (1) and [Co8(OH)(ina)8(N3)8·X] with dual tetra-nuclear cobalt nodes (2), have been synthesized under hydrothermal conditions by utilizing the template agent of pentaerythritol. 1 shows a 2D layer comprised of linear tri-nuclear CoII clusters, in which the central cobalt ion is inter-linked with two terminal ones via mixed bridges as syn–syn carboxylates and end-on azide ions. In contrast, compound 2 exhibits a three-dimensional framework based on two kinds of six-connected tetra-nuclear cobalt clusters: square-planar node and cuboidal node. Both 1 and 2 might exhibit spin-canted magnetism. In addition, the activated sample of 2 exhibits the sorption ability of H2 and CO2 molecules. [ABSTRACT FROM AUTHOR]

A single crystal composed of one-dimensional coordinated polymers, [CdCl 2 (1-methyl-2-pyridone)] n , has been synthesized and characterized. This compound exhibits outstanding elastic bending due to the molecular spring nature of the CdCl 2 coordination framework and weak intermolecular interactions between the coordination chains. Owing to the helical arrangement of organic ligands surrounding the coordination structure, the compound crystallizes in a chiral space group. As a result, it displays compelling circular dichroism spectra and second harmonic generation properties.

In this paper, we report a two-dimensional (2D) Hofmann-type spin-crossover coordination polymer [Fe II ( o -NTrz) 2 Pt II (CN) 4 ]·H 2 O ( o -NTrz = 4-( o -nitrobenzyl)imino-1,2,4-triazole). Due to the remarkable configurational flexibility of triazole-based ligand, the porous structure of this compound can be reversibly regulated by the loss of guest water molecules as a consequence of rotation of o -NTrz. The 180° reorientation of the o -nitrobenzyl moiety not only induces a response of gate-closing/opening of the porous framework but also significantly modulates the spin transition temperature. The present investigation highlights the potential of Hofmann-type SCO compounds with flexible ligands in exploring unusual physical and chemical phenomena.

Herein, we report a twisted cubic Cu(I) 4 Ti(IV) 4 -oxo cluster stabilized by in situ - formed 2,2'-biphenolate ligands from the oxidative coupling of phenols. The 2,2'-biphenolate-functionalized Cu(I) 4 Ti(IV) 4 O 4 cluster shows short Cu⋯C contacts and exhibits smaller HOMO-LUMO gaps than those of reported Ti(IV) 4 O 4 .

Spin-crossover (SCO) materials have been extensively investigated in the past few decades with promising applications in a wide range of fields including displays, sensors, and storage components. The introduction of secondary physical properties to SCO materials resulting in bifunctional materials is becoming a research hot spot. In particular, for the fluorescent SCO materials, fluorescence can serve as a sensitive probe that easily expresses the spin-state changes of SCO materials; therefore, fluorescent SCO bifunctional materials have promising applications in the fields of magneto-optical switching and information processing. In this perspective, we briefly review the main synthetic strategies and progresses in fluorescent SCO materials in the last twenty years.

We report a phosphine-directed ruthenium-catalyzed C8-selective alkylation of naphthalenes with alkenes. This protocol provides straightforward access to a large library of electron-rich C8-alkyl substituent 1-naphthphosphines, which outperformed common commercial phosphines and their precursors in the Pd-catalyzed Suzuki-Miyaura coupling of aryl bromides with alkylboronic acid.

A series of dynamic single crystals with a chemical formula of [M II (en) 3 ]SO 4 (en = ethylene and M II = Ni II , Mn II , and Cd II ) was synthesized. As the temperature decreases, these materials exhibit dielectric switching in the vicinity of the phase transition point accompanied by anisotropic thermal expansion in the cell parameters as a consequence of the order-disorder structural change of SO2-4 in a cavity surrounded by five [M II (en) 3 ] 2+ complex cations. Because the variation of metal centers with different ionic radii changes the shape of the complex cation, which affects the distribution of hydrogen-bond interactions around the SO2-4, the dynamic motion of SO2-4 is substantially tuned. Correspondingly, the dielectric properties and anisotropic thermal expansion of materials were largely shifted, especially in the single crystals of [Mn II (en) 3 ]SO 4 , whose structural change is distinctly different from the crystals of Ni(II) and Cd(II). The detailed structural mechanism accounting for the different physical properties of these materials was discussed.

A mononuclear complex with long alkyl chains, [Fe II (H 2 Bpz 2 ) 2 (C 9 bpy)] (1; H 2 Bpz 2 = dihydrobis(1-pyrazolyl)borate, C 9 bpy = 4,4'-dinonyl-2,2'-bipyridine), was synthesized. Single-crystal X-ray crystallographic studies revealed that the Δ- and Λ-forms of the complex co-crystallized in the lattice asymmetric unit, while magnetic measurements unveiled that this complex underwent incomplete one-step spin crossover (SCO) with the transition completeness and temperature depending on the measurement velocity because of slow spin equilibrium. Multivariable approaches such as varying scan rate, annealing the sample, light irradiation and pressure have been adopted to effectively overcome the slow spin equilibrium and thus improve the SCO completeness.

Hofmann-type spin-crossover (SCO) frameworks attract much attention due to their predictable structures and diverse SCO behaviours. In this paper, we report two isostructural two-dimensional (2D) Hofmann-type SCO frameworks [FeII(ppe)2MII(CN)4]·3H2O (ppe = 1-(2-pyridyl)-2-(4-pyridyl)ethylene and M = Pd for 1 and Pt for 2). X-ray crystallographic studies, magnetic measurements and Mössbauer spectra jointly reveal that both compounds undergo complete hysteretic two-step SCO, i.e. HS1.0 ⇌ HS0.6-0.5LS0.4-0.5 ⇌ LS1.0 conversion with thermal hysteresis loops of 14 K and 28 K wide for 1 and 13 K and 26 K wide for 2. The dehydrated samples, 1-dehydrated and 2-dehydrated, display different SCO behaviours, unveiling that the SCO behaviours are affected by guest water molecules.

Reversible single crystal-to-single crystal transformations from [FeL 2 (NCS) 2 ]·3MeOH (1·3MeOH, L = 2-(anthracen-10-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) to 1 and 1·2H 2 O were reported, which were accompanied by on-off switching of the spin-crossover properties.

Three one-dimensional looped coordination polymers with the formula of [Fe(dpds)2{C(CN)3}2]·dpds (1, dpds = 4,4'-dipyridyl disulfide), [Fe(dpds)2(NCBH3)2] (2) and [Fe(dpds)2(NCSe)2]·3.5H2O (3) have been synthesized and characterized by single-crystal X-ray crystallography, Mössbauer spectroscopy and magnetic measurements. The spin-crossover (SCO) behaviors of these compounds depend significantly on axial ligands: compound 1 exhibited thermal-induced complete one-step SCO behavior with a T1/2 of 170 K, and 2 showed incomplete SCO behavior with T1/2 being 130 K, whereas 3 was paramagnetic. Meanwhile, both compounds 1 and 2 displayed light-induced excited spin-state trapping (LIESST) effects, featuring TLIESST values of 45 K and 61 K for 1 and 2, respectively, which were independent of exciting laser wavelengths. These results suggest that anions such as C(CN)3- and NCBH3- with much stronger ligand fields are needed in order to realize spin-state switching, if a ligand such as dpds is adopted to synthesize SCO compounds.