The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate~s! and trapping the folding intermediate~s! into enzymatically inactive, "aggregation-insensitive" state~s!. However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations~Ͼ1.5 M!, proline is shown to form loose, higher-order molecular aggregate~s!. The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone.

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The first metal carboxylatophosphate, NTHU-2, contains inorganic ZnHPO4 layers linked by BDC units (BDC = 1,4-benzene dicarboxylate or terephthalic anion); the three-dimensional anionic framework has large pores with the smallest diameter being 1.36 nm; N2 sorption isotherms reveal both micro- and mesoporosity; the new material is photoluminescent and disassembles in water wherein the discharged organic fragments form mixed crystals.

Four photoluminescent dye crystals, TPB-n (n = 1-3) and TPCH, have been synthesized in isolation from carbon-carbon coupling of 4,4'-trimethylene-dipyridine (tmdp) in the absence of organic solvent and catalyst via in situ one-pot metal/ligand oxidative-dehydrogenation reactions. Large crystals have been obtained and readily separated from reaction products without the need for purification. Their structures were characterized: TPB and TPCH represent two dissimilar oxidized forms of tmdp dimers; TPCH was less oxidized but accompanied with partial hydrolysis with molecular formula further confirmed by FAB-MASS analysis. They exhibit distinct photoluminescence (PL) with quantum efficiency measured up to 42%. TPB-2 and TPB-3 are two polymorphic dihydrates, stimuli-responsive toward photoluminescence color changes; both can transform to TPB-1 upon gentle heating. Importantly, the three TPB-n crystals establish the first tetrapyridyl-type ligands adapted by metal phosphates to create a cationic luminescent framework, NTHU-12. This study serves as an inspiring route beyond conventional C-C bond formation reactions and has generated four tmdp dimers in isolation. The facile syntheses have resulted in ample production of a rare type of tetrapyridyl ligands, leading to the discovery of the first positively charged hybrid topology in nanoporous solids. The features of the four luminescent tmdp dimers and NTHU-12 embodied in synthesis, structure, and optical property are reported.

A metal‐activator‐free orange phosphor was synthesized from ZnO/H3PO3/diamine in choline chloride/oxalic acid deep eutectic solvent, which also acted as methylating agent and source of ethylene glycol (EG) by dissociation of choline ions. Interlayer incorporation of a dimethylated amine made the resulting layered zinc phosphate (“ZnPO”, see picture) photochromic, and their interaction with EG formed fluorophores with orange photoluminescence.

Cluster. -The new intrinsic yellow phosphor (II) crystallizes in the monoclinic space group C2/m with Z = 4 (single crystal XRD). The structure contains octahedral Ga6(OH)4O26 hexamers which are interlinked to microporous octahedra-oxalate hybrid sheets. Each hexamer is also connected to 6 GaO4 and 10 PO4 tetrahedra to form 22-polyheral secondary building units, which are further connected to a three-dimensional hybrid framework with nm-sized channels. Under excitation over the broad range 360-500 nm (II) emits yellow (540 nm) luminescence with a photoluminescence quantum efficiency of up to 42%.

A metal-organic framework (MOF) material was integrated with surface superhydrophobicity, high surface areas, large and uniform pore sizes, and excellent stability. This synthetic procedure was completed via an encapsulationrearrangement strategy. Benefiting from the superhydrophobicity, this MOF could be stable in humid environments and maintained its mesoporosity and surface areas for at least 6 months. The MOF-modified sponge has great potential in applications such as oil/water separation, water remediation, and heterogeneous catalysis.

Treatment of tungsten-η 1 -R,δ-and -η 1 -R, -alkynols 4-6 with RCHO/BF 3 ‚Et 2 O (R ) alkyl, aryl) in cold diethyl ether effected cycloalkenation reaction, yielding tungsten-η 1 -furylidene and -η 1 -pyrylidene salts in excellent yields (>95%). The structures of these oxacarbeniums were elucidated through X-ray diffraction studies of the representative compounds 7 and 8 in addition to standard NMR and IR spectral data. In contrast with conventional metal carbeniums, these tungsten oxacarbeniums reacted with two molecules of nucleophiles such as H 2 O, NaBH 3 CN, and Grignard reagents, resulting in R,R-double addition reactions to afford furan and pyran derivatives in good yields. In the hydride case, unsymmetric R,R-double addition of η 1 -furylidenium salts was achieved via treatment with NaBH 4 /MeOH. Organocuprates also effected double alkylations of these salts but in a distinct 1,3addition pathway. The reactions of these oxacarbeniums with CH 2 N 2 were examined; the outcome depends on their vinyl substituents. When the substituent is an aliphatic group, the carbenium species undergo highly diastereoselective cyclopropanation with CH 2 N 2 . For an aryl substituent, the reaction with CH 2 N 2 yielded a new tungsten oxacarbenium with a significantly altered structure; in this case 13 C-and 2 H-labeling experiments were performed to elucidate the reaction mechanism.