Propane/propene separation by cryogenic distillation is one of the most energy and cost intensive industrial processes. Adsorptive separation is a more energy-efficient alternative. Three isostructural zinc imidazolate zeolitic framework materials are found, for the first time, to be very promising in the separation of propene and propane based on their different diffusion rates. Fine-tuning of the pore opening size is critical for this type of separation.

Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.

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The design, synthesis, and structural characterization of two new microporous metal‐organic framework (MMOF) structures is reported; Zn(BDC)(DMBPY)0.5·(DMF)0.5(H2O)0.5 (1; H2 BDC = 1,4‐benzenedicarboxylic acid; DMBPY=2,2′‐dimethyl‐4,4′‐bipyridine) and Zn(NDC)(DMBPY)0.5·(DMF)2 (2; H2NDC = 2,6‐naphthalenedicarboxylic acid, DMF=N,N,‐dimethylformamide), which are obtained by functionalizing a pillar ligand with methyl groups. Both compounds are 3D porous structures of the Zn2(L)2(P) type and are made of a paddle‐wheel Zn2(COO)4 secondary building unit (SBU), with the dicarboxylate and DMBPY as linker (L) and pillar (P) ligands, respectively. Comparisons are made to the parent structures Zn(BDC)(BPY)0.5·(DMF)0.5(H2O)0.5 (3; BPY = 4,4′‐bipyridine) and Zn(NDC)(BPY)0.5·(DMF)1.575 (4) to analyze and understand the effect of methyl functionalization. CO2‐adsorption studies indicate substantially enhanced isosteric heats of CO2 adsorption (Qst) for both compounds, as a result of adding methyl groups to the BPY ligand. The CO2 uptake capacity, however, is affected by two opposing and competing factors: the enhancement due to increased MMOF–CO2 interactions (higher Qst values) and detraction due to the surface area and pore‐volume reduction. For 1′ (the guest‐free form of 1), the positive effect dominates, which leads to a significantly higher uptake of CO2 than that of its parent structure 3′ (the guest‐free form of 3). In 2′ (the guest‐free form of 2), however, the negative effect rules, which results in a slightly lower CO2 uptake with respect to 4′ (the guest‐free form of 4). All four compounds exhibit a relatively high separation capability for carbon dioxide over other small gases, including CH4, N2, and O2. The separation ratios of CO2 to O2 and N2 (at 298 K and 1 atm) are 39.8 and 23.5 for compound 1′, 57.7 and 40.2 for 2′, 25.7 and 29.5 for 3′, 89.7, and 20.3 for 4′, respectively. IR and Raman spectroscopic characterization of CO2 interactions with 1′ and 2′ provides indirect support of the importance of the methyl groups in the interaction of CO2 within these systems.

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Single-phased white light emitters made of semiconductor bulk materials are most desirable for use in white light-emitting diodes (WLEDs) based on both photoluminescence and electroluminescence. Here we demonstrate Cd and/or Se substituted double-layer [Zn 2 S 2 (ha)] (ha = nhexylamine) hybrid semiconductors emit bright white light in the bulk form and their emission properties are systematically tunable. The ternary Zn 2−2x Cd 2x S 2 (ha) hybrid compounds exhibit two photoluminescence (PL) emission peaks, one of which being attributed to band gap emission, and the other resulting from Cd doping and surface sites. The Cd concentration modulates the optical absorption edge (band gap) and the positions of the two emission bands along with their relative intensities. The ZnS-based hybrid structures (with a nominal Cd mole fraction x = 0.25) emit bright white light with significantly enhanced photoluminescence quantum yield (PLQY) compared to its CdS-based hybrid analogues. For the quaternary Zn 2−2x Cd 2x S 2−2y Se 2y (ha) compounds (x = 0.25 and different nominal Se mole fractions y) the synergetic effect between doped Cd and Se atoms leads to further tunability in the band gap and emission spectra, yielding well balanced white light of high quantum yield. Detailed analysis reveals that the PL emission properties of the ternary and quaternary hybrid semiconductors originate from their unique double-layered nanostructures that combine the strong quantum confinement effect and large number of surface sites. The white-light emitting hybrid semiconductors represent a new type of single-phased phosphors with great promise for use in WLEDs.