Acetylene (C 2 H 2 )c apturei sastep in an umber of industrial processes, but it comes with ah igh-energy footprint. Although physisorbents have the potential to reduce this energy footprint, they are handicappedb y generally poor selectivity versusother relevant gases, such as CO 2 and C 2 H 4 .I nt he case of CO 2 ,t he respective physicochemical properties are so similar that traditional physisorbents, such as zeolites, silica, anda ctivated carbons cannot differentiate well between CO 2 and C 2 H 2 .H erein, we report that af amily of three isostructural, ultramicroporous (< 7 )d iamondoidm etal-organic frameworks, [Cu(TMBP)X] (TMBP = 3,3',5,5'-tetramethyl-4,4'-bipyrazole), TCuX (X = Cl, Br,I ), offer new benchmark C 2 H 2 /CO 2 separation selectivity at ambient temperature and pressure.W e attribute this performance to an ew type of strong binding site for C 2 H 2 .S pecifically,h alogen···HC interactions coupledw ith othern oncovalent in at ight binding site is C 2 H 2 specific versus CO 2 .T he binding site is distinct from those found in previous benchmark sorbents, which are based on open metal sites or electrostatic interactionse nabled by inorganic fluoro or oxo anions.That C 2 H 2 poses an immediate fire and explosive hazard at > 2.5 %c oncentrations and features the widest knownf lammability range, [1] 2.5-81 %, underscores the need to develop energy-efficient C 2 H 2 -capture sorbent materials. [2] Further,i ts high reactivity can lead to undesirable chemicalr eactions duringi ndustrial processes, for example, traces of C 2 H 2 can poisonc atalystsb yf orming metal acetylides duringe thylene polymerization, leading to explosions. [3] Removal of C 2 H 2 as a trace contaminant is also important in the productiono fa crylic/vinyl derivatives and acetylenic alcohols. [4] With respect to bulk usage,C 2 H 2 is the most common gas used to fuel cutting torches. C 2 H 2 recovered in high purity can serve as af uel or buildingblock in polymer synthesis for example, polyvinyl chloride, PVC and polyvinylidene fluoride,PVDF. [4] In C 2 H 2 manufacturedb yp artial combustion (oxidative coupling)o fmethane [5] or thermal cracking of hydrocarbons, CO 2 is generated as ab y-product. [6] To enable C 2 H 2 capturef rom C 2 H 2 /CO 2 mixtures, three current methods were employed: 1) bulk extraction by organic solvents, for example, N,N-dimethylformamide, and acetone; [7] b) partial hydrogenation of C 2 H 2 to ethylene, C 2 H 4 using expensive Ag 0 /other noble-metalc atalysts; [8] and c) cryogenic distillation. [9] All three approaches are costly and energy intensive. Althoughp hysisorbentso ffer potentialf or reducing the energyf ootprint of C 2 H 2 capture, zeolites, silica, and activated carbonsc annot effectively separate C 2 H 2 from CO 2[10] because of their similarp hysicochemical properties (size:C 2 H 2 = 3.32 3.34 5.7 3 ;C O 2 = 3.18 3.33 5.36 3 ;k inetic diameter = 3.3 for both;b oilingp oint:C 2 H 2 = 189.3 K, CO 2 = 194.7 K). [11] In this context,a ne merging class of physisorbents, namely, metal-organic m...

The series of highly stable porous solids here feature systematic, regiospecific sulfur substitutions on the organic linkers for versatile functions. One major surprise lies in the controllable sequential reactions between sodium thiomethoxide (NaSMe) and octafluorobiphenyl-4,4′-dicarboxylic acid (H 2 bpdc-8F; this was readily made without precious metal catalysts). Namely, 3, 4, 6, and 8 methylthio-substitutions can be respectively achieved with regiospecificity (i.e., to produce the four molecules H 2 bpdc-3S5F, H 2 bpdc-4S4F, H 2 bpdc-6S2F, H 2 bpdc-8MS). A second surprise lies in their persistent formation of the UiO-67type net with Zr(IV) ions, e.g., even in the case of the fully sulfurated H 2 bpdc-8MS. In addition to the remarkable breadth of functional control, all the Zr(IV)-based crystalline solids here are stable in boiling water (e.g., for 24 h) and in air as solventless, activated porous solids. Moreover, the thioether groups allow for convenient H 2 O 2 oxidation to fine-tune the hydrophilicity and luminescence properties and improve proton conductivity.Article pubs.acs.org/IC

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Breaking the cycle of silver pyrazolates: instead of the common loops (e.g., the Ag3N6 ring), we report an infinite array in which the equispaced Ag­(I) ions form a zigzag chain, with the associated anthracene bis­(pyrazolate) linkers cofacially aligned one to another. In addition to the strong Ag­(I)–N bonds and the distinct argentophilic interactions, the Ag­(I) ions also form interlayer, metal−π contacts with the anthracene cores. The resultant two-dimensional network exhibits significant electronic interaction between the Ag­(I) centers and the large aromatic linker molecule, as revealed by the red shift of photoemission spectra and the significant reduction of the electronic band edge as determined by diffuse reflectance spectroscopy. The solid sample is stable in air and water.

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