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The π⋯π interactions in spin crossover (SCO) complexes can be used as an important means to fine-tune the spin transition behaviors. In this paper, three novel isostructural 2D Hofmann-type frameworks, [Fe(ppo)2M(CN)4] (1, M = Pt2+; 2, M = Pd2+; 3, M = Ni2+) have been successfully synthesized by judiciously choosing a large conjugated molecule, 2-(2-pyridyl)-5-(4-pyridyl)-1,3,4-oxadiazole (ppo) as the axial ligand. Single crystal X-ray crystallography analysis showed that there are different π⋯π interactions between the axial ppo ligands in 1–3. Variable temperature magnetic susceptibility studies revealed that 1 and 3 displayed incomplete and gradual SCO behaviors with T1/2 = 94 and 78 K, respectively, while 2 stayed in a high-spin state in the measured temperature range. The stronger π⋯π interactions between the conjugated ppo ligands observed in 1 and 3 than those in 2 may result in their different magnetic behaviors. [ABSTRACT FROM AUTHOR]

The value of functional pyrrolidines in the fields of biology, pharmacology, catalysis, and natural product synthesis stimulates an intensive interest in developing new synthetic methods for this class of compounds, and direct functionalization of the simple pyrrolidine represents an attractive and effective approach. Herein, a metal-free protocol for direct N -arylation and α-functionalization of pyrrolidine via redox-neutral three-component reactions is reported, in which p -quinol ethers or p -quinone monoacetals serve as the arylation components and the formal oxidants for α-functionalization of pyrrolidine. [ABSTRACT FROM AUTHOR]

Herein, we report the pyrrolidine‐catalyzed annulation reaction of p‐quinone monoacetals with naphthols at room temperature. The reaction is also extended to including 4‐hydroxycoumarin, 4‐hydroxy‐1‐methylcarbostyril, 4‐hydroxycarbostyril, and several β‐ketoesters as the nucleophiles, thereby providing a collection of bridged cyclic compounds bearing 2‐oxabicyclo[3.3.1]nonane skeletons in 41–96% yields. The reaction can be adapted to gram‐scale synthesis, and several transformations of the obtained bridged cyclic products are demonstrated for the preparation of polycyclic compounds that may find utility in related fields. Mechanism studies indicate the engagement of iminium intermediate in the reaction, and a bridged ring enamine intermediate can be observed by NMR. [ABSTRACT FROM AUTHOR]

An unprecedented bird‐nest high‐nuclear molybdenum(V) cobalto‐phosphate nanosized wheel modified by imidazole (im) and pyridine (py), {[H55(Mo24O48)(Co4O)2Co16(PO4)42(py)6(EtOH)2(H2O)11]‐ @[(Him)2(Hpy)]}(N‐Et‐py)(H2PO4)(py)7(EtOH)⋅12 H2O (1), has been successfully synthesized by self‐assembly. The anionic huge wheel consists of two rare {Co4O} squares, four {Co4} tetramers, four {Mo4} tetramers and four {Mo2} dimers, linked by bridging oxygen atoms and [PO4] groups and encloses two imidazolium cations and a protonated pyridium for charge balance. Surprisingly, 1 represents the first twisted wheel‐shaped cluster with a record high‐nuclear molybdenum(V) cobalto‐phosphate. The delocalized electron effects of the cluster are enhanced with the help of coordinated py ligands, which endows 1 with an excellent third‐order nonlinear optical (NLO) response. Additionally, 1 also shows a better photocatalytic water oxidation activity than Co(NO3)2 with the O2 production of 205 μmol during 6 h in the absence of the [Ru(bpy)3]2+ photosensitizer. [ABSTRACT FROM AUTHOR]

The three‐component reaction of p‐quinone monoacetals, amines and diarylphosphine oxides is developed to afford m‐(diarylphosphinyl)anilides in moderate to high yields. The reaction may proceed via a process involving phospha‐nucleophilic addition to an iminoquinone acetal intermediate and/or carbonyl‐amine condensation with a phosphinyl enone intermediate. [ABSTRACT FROM AUTHOR]

Bifunctional ligands containing both carboxylic and sulfonate groups can adopt versatile coordination modes to produce novel metal–organic frameworks (MOFs) with high‐dimensional networks and interesting topologies. Using 2,2′‐disulfonylbiphenyl‐4,4′‐dicarboxylic acid (H4L) as a linker and 4,4′‐bipyridine (4,4′‐bpy) as a co‐ligand, two novel 3D CuII MOFs, {[Cu2(L)(4,4′‐bpy)2.5(H2O)]·1.7H2O}n, (1), and {[Cu2(L)(4,4′‐bpy)2]·DMA·3H2O}n, (2), have been synthesized and structurally characterized by X‐ray crystallography (DMA is N,N‐dimethylacetamide). MOF (1) shows an unprecedented trinodal 4,4,5‐connected topology network with the Schläfli symbol (4.62.73)(43.65.7.8)(6.73.8.10), while MOF (2) indicates a binodal 4,6‐connected fsc network with the Schläfli symbol (44.610.8)(44.62). MOFs (1) and (2) were further characterized by elemental analysis, IR spectroscopy, powder X‐ray diffraction and thermogravimetric analysis. MOF (1) shows a high water and chemical stability. The proton conductivity of (1) and CO2 adsorption of (2) were also investigated. [ABSTRACT FROM AUTHOR]