Host-Host Interactions Enhanced the Structural Rigidity in a 6-Fold Interpenetrated Diamondoid Metal-Organic Framework Exhibiting CH/CH Separation.

Multi-interpenetrated metal-organic frameworks (MOFs) have exhibited excellent performance in selective adsorption due to the variable post-interspersed flexibility, but the design and control remain challenging. Herein, two anthracene-based ligands, 4,4'-(anthracene-9,10-diyl)dibenzoic acid (HL1) and 9,10-di(pyridin-4-yl)anthracene (L2), are used to construct a new three-dimensional 6-fold interpenetrated MOF [Zn(L1)(L2)] (), which exhibits multiple C-H···π interactions that enhance the structural rigidity, thereby entangling with a CH/CH separation performance. In this material, the incorporation of abundant anthracene rings within the framework not only partitions and restricts the pore window size to a quasi-double pore but also stabilizes it through host-host interactions.

Guest water-induced structural transformation and spin-crossover variation of a two-dimensional Hofmann-type compound.

In this paper, we report a two-dimensional (2D) Hofmann-type spin-crossover coordination polymer [Fe(-NTrz)Pt(CN)]·HO (-NTrz = 4-(-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 -NTrz. The 180° reorientation of the -nitrobenzyl moiety not only induces a response of gate-closing/opening of the porous framework but also significantly modulates the spin transition temperature.

Stepwise Synthesis of Cl-Decorated Trinuclear-Cu Cluster-Based Frameworks for CH/CH and CH/CO Separation.

A novel Cl-decorated trinuclear-Cu cluster-based MOF (, NbU denotes Ningbo University) was synthesized by a stepwise synthesis strategy. Compared to one-step reactions, the strategy of combining cationic templates with single-crystal-to-single-crystal transformation provides more possibilities for the design and postsynthetic modification of multifunctional materials. Note that the chloride ions are attached to the copper ions of the planar trinuclear cluster nodes in a fully symmetric or partially asymmetric manner.

Two-Dimensional Coordination Polymer Showing Spin-Crossover Behavior with a 64 K Wide Hysteresis Loop.

A two-dimensional grid-like coordination polymer, [Fe(NCBH)(Pyttz)]·4CHCl (, Pyttz = 2,5-di(pyridin-4-yl)thiazolo[5,4-]thiazole), showed one-step complete spin crossover with unexpectedly large hysteresis loop of 64 K wide and temperature-induced excited spin-state trapping effect below 91 K.

Synergistic valence tautomerism and fluorescence emission in a two-dimensional coordination polymer.

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.

Synergistic strategies for the synthesis of Fe(II)-based bifunctional fluorescent spin-crossover materials.

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.

A spin-crossover framework endowed with pore-adjustable behavior by slow structural dynamics.

Host-guest interactions play critical roles in achieving switchable structures and functionalities in porous materials, but design and control remain challenging. Here, we report a two-dimensional porous magnetic compound, [Fe(prentrz)Pd(CN)] (prentrz = (1E,2E)-3-phenyl-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine), which exhibits an atypical pore transformation that directly entangles with a spin state transition in response to water adsorption. In this material, the adsorption-induced, non-uniform pedal motion of the axial prentrz ligands and the crumpling/unfolding of the layer structure actuate a reversible narrow quasi-discrete pore (nqp) to large channel-type pore (lcp) change that leads to a pore rearrangement associated with simultaneous pore opening and closing.

Giant single-crystal-to-single-crystal transformations associated with chiral interconversion induced by elimination of chelating ligands.

Numerous single crystals that exhibit single-crystal-to-single-crystal (SCSC) transformations have been reported, and some of them show great promise for application to advanced adsorption materials, magnetic switches, and smart actuators. However, the development of single crystals with super-adaptive crystal lattices capable of huge and reversible structural change remains a great challenge. In this study, we report a Zn complex that undergoes giant SCSC transformation induced by a two-step thermal elimination of ethylene glycol chelating ligands.

Spin-crossover iron(ii) long-chain complex with slow spin equilibrium at low temperatures.

A mononuclear complex with long alkyl chains, [Fe(HBpz)(Cbpy)] (1; HBpz = dihydrobis(1-pyrazolyl)borate, Cbpy = 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.

Reverse Hofmann-Type Spin-Crossover Compound Showing a Multichannel Controllable Color Change in an Ambient Environment.

Materials that demonstrate a multichannel controllable color change in response to external stimuli are fascinating for their potential applications in sensoring and displaying devices. Herein we report a Fe spin-crossover (SCO) compound that exhibits both solvatochromism and thermochromism under an ambient environment. This Hofmann-type compound possesses two different pores where the solvent guests can be removed in a two-step process.

Giant Single-Crystal Shape Transformation with Wide Thermal Hysteresis Actuated by Synergistic Motions of Molecular Cations and Anions.

Manipulating the collective molecular movements to implement macroscopic mechanical response of bulk material is attractive and challenging. Here, an organic-inorganic hybrid single crystal is synthesized, which exhibits a giant macroscopic shape transformation with a remarkable thermal hysteretic feature. The colossal anisotropic shape change, which manifests as an abrupt elongation of ca.

Switchable on-off spin-crossover properties of iron(ii) compounds by trimming intermolecular hydrogen bonds.

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

A Two-Dimensional Spin-Crossover Coordination Polymer Exhibiting Interlayer Multiple C-H···H-B Dihydrogen Bonds.

The reaction of 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene (tppe) with [Fe(NCBH)] produced a two-dimensional coordination polymer [Fe(NCBH)(tppe)] (), which was pillared in an ABAB manner through interlayer multiple [C-H···H-B] dihydrogen bonds (DHBs) to form a stable porous three-dimensional (3D) supramolecular structure that showed guest-molecule-dependent spin-crossover behaviors.