Microenvironment Modulation of Metal-Organic Frameworks (MOFs) for Coordination Olefin Oligomerization and (co)Polymerization.

The majority of commercial polyolefins are produced by coordination polymerization using early or late transition metal catalysts. Molecular catalysts containing these transition metals (Ti, Zr, Cr, Ni, and Fe, etc.) are loaded on supports for controlled polymerization behavior and polymer morphology in slurry or gas phase processes. Within the last few years, metal-organic frameworks (MOFs), a class of unique porous crystalline materials constructed from metal ions/clusters and organic ligands, have been designed and utilized as excellent supports for heterogeneous polymerization catalysis whose high density and uniform distribution of active sites would benefit the modulations of molecular weight distributions of high-performance olefin oligomers and (co)polymers. Impressive efforts have been made to modulate the microenvironment surrounding the active centers at the atomic level for improved activities of MOFs-based catalysts and controlled selectivity of olefin insertion. This review aims to draw a comprehensive picture of MOFs for coordination olefin oligomerization and (co)polymerization in the past decades with respect to different transition metal active centers, various incorporation sites, and finally microenvironment modulation. In consideration of more efforts are needed to overcome challenges for further industrial and commercial application, a brief outlook is provided.

Response to the Temperature and Solvent Stimulation of MOF Material in a Single-Crystal to Single-Crystal Manner.

Under solvothermal conditions, a three-dimensional mononuclear crystal AQNU-1, {[Co(H2L)(DPD)(H2O)2]·2DMA}n (H2L = 5-(bis(4-carboxybenzyl)amino)isophthalic acid, DPD = 4,4'-(2,5-diethoxy-1,4-phenylene)dipyridine) has been synthesized. The transformations of AQNU-1 to binuclear {[Co2(L)(DPD)1.5(H2O)3]·DMA·H2O}n (AQNU-2) and pentanuclear {[Co5(L)2(DPD)2(OH)2]·2H2O}n (AQNU-3) were realized by double stimulation of temperature and solvent, which were accomplished by single-crystal to single-crystal (SC-SC) reaction.

Effectiveness and Safety of Anlotinib with or without PD-1 Blockades in the Treatment of Patients with Advanced Primary Hepatocellular Carcinoma: A Retrospective, Real-World Study in China.

Purpose: Anlotinib, a novel multi-target tyrosine kinase inhibitor, has shown encouraging antitumor effects in advanced hepatocellular carcinoma (HCC). This study evaluated the effectiveness and safety of anlotinib with or without programmed death-1 (PD-1) blockades for patients with advanced primary HCC in a real-world setting in China. Patients and Methods: Between July 2019 and May 2021, 27 patients with advanced primary HCC who received at least 2 cycles of anlotinib were included in this retrospective study. Primary endpoint was objective response rate (ORR). Secondary endpoints were disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety. Results: Of the 27 patients, ORR and DCR were 25.93% and 74.07%, respectively. The median follow-up time was 6.27 months (range: 1.30-17.40) with a median PFS and OS of 3.29 months (95% CI: 1.31-15.47) and 6.21 months (95% CI: 2.23-15.87), respectively. A total of 14 patients received anlotinib and PD-1 blockade combination therapy, and 13 received anlotinib monotherapy. No significant differences were observed in ORR (28.57 vs 23.08%), DCR (71.43 vs 76.92%), PFS (3.38 [95% CI: 2.66-13.14] vs 11.86 months [95% CI: 4.27-15.93]) and OS (4.90 [95% CI: 2.56-13.60] vs 11.04 months [95% CI: 1.31-17.18]) between the two groups (all p>0.05). Treatment-related AEs were reported in 88.89% of patients. Grade 3 AE was bleeding, which occurred in 3 patients (11.11%). Conclusion: Anlotinib yielded a promising efficacy and manageable safety in patients with advanced primary HCC irrespective of whether patients received PD-1 blockades, indicating that anlotinib might be a promising treatment option for this patient population.

Light- and temperature-assisted spin state annealing: accessing the hidden multistability.

Among responsive multistable materials, spin crossover (SCO) systems are of particular interest for stabilizing multiple spin states with various stimulus inputs and physical outputs. Here, in a 2D Hofmann-type coordination polymer, [Fe(isoq)2{Au(CN)2}2] (isoq = isoquinoline), a medium-temperature annealing process is introduced after light/temperature stimulation, which accesses the hidden multistability of the spin state. With the combined effort of magnetic, crystallographic and Mössbauer spectral investigation, these distinct spin states are identified and the light- and temperature-assisted transition pathways are clarified. Such excitation-relaxation and trapping-relaxation joint mechanisms, as ingenious interplays between the kinetic and thermodynamic effects, uncover hidden possibilities for the discovery of multistable materials and the development of multistate intelligent devices.

An excellent example illustrating the fluorescence sensing property of cobalt-organic frameworks.

A novel luminescent cobalt-organic framework was assembled and employed as a chemosensor for the detection of metal ions via fluorescence enhancement and quenching. The sensing mechanism was based on the exposed pyridyl and carboxyl functional sites in the MOF structure, which interacted with metal ions via Lewis acid-base interactions and electrostatic interactions.

Diverse structures of metal-organic frameworks based on different metal ions: luminescence and gas adsorption properties.

Four coordination polymers with different metal ions have been synthesized based on a rigid linear pyridine and a flexible V-shaped dicarboxylate ligand (L = 4,4'-(2,5-dimethoxy-1,4-phenylene)dipyridine; H2OBA = 4,4'-oxydibenzoic acid): {[Co(L)(OBA)]·2H2O}n (1), [Zn(L)(OBA)·2H2O]n (2), {[Ni(L)(OBA)]·DMF·H2O}n (3), [Cd(L)(OBA)]·DMF·H2O}n (4). The reaction conditions are similar except for the metal ions for complexes 1-4. Complexes 1 and 2 present a 3D unprecedented hxg-d-4-Cccm net, but 3 and 4 are 4-connected sql nets with a point symbol {4(4)·6(2)}. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. The UV-visible spectra, fluorescence, and gas adsorption properties of the compounds were also explored.

Three different metal-organic frameworks derived from a one-pot crystallization and their controllable synthesis.

Three different Co-MOFs, [Co3(L)2(DPDP)]n (1), [Co(HL)(DPDP)]n (2) and {[Co(HL)(1/2DPDP)3(H2O)]·H2O}n (3) (H3L = 4,4',4''-(nitrilotris(methylene))tribenzoic acid, DPDP = 4,4'-(2,5-dibutoxy-1,4-phenylene)dipyridine) have been co-crystallized in a one-pot reaction. Based on the significant differences between the three structures, we adopt solvents to ultimately regulate acquisition of pure crystals of the three compounds.

Assembly of various degrees of interpenetration of Co-MOFs based on mononuclear or dinuclear cluster units: magnetic properties and gas adsorption.

Three new Co-based MOFs with a nanosized tetradentate pyridine ligand, N,N,N',N'-tetrakis(4-(4-pyridine)-phenyl) biphenyl-4,4'-diamine (TPPBDA) and carboxylate co-ligands, [Co(TPPBDA)(NO3)2]n·2H2O (1), [Co2(TPPBDA)(bpdc)2 (H2O)]n·2DMA (2) and [Co(TPPBDA)0.5(hfipbb)(H2O)]n·3.5H2O (3) (H2bpdc = biphenyldicarboxylic acid, H2hfipbb = 4,4'-(hexafluoroisopropylidene)bis-(benzoic acid), DMA = N,N-dimethylacetamide) have been synthesized under hydrothermal conditions. For complex 1, a large cavity causes a 4-fold interpenetration of the network, which can be classified as a type IIIa mode of interpenetration. Complex 2 reveals a non-interpenetrating three-dimensional (3D) framework based on the [Co2(µ2-H2O)(CO2)2] unit. Complex 3 is also a 2-fold interpenetrating 3D net based on the [Co2(CO2)2] cluster. These mononuclear or dinuclear cluster units are interconnected by TPPBDA and carboxylate co-ligands, resulting in interesting structural diversities and various degrees of interpenetration.