An Anion Metal-Organic Framework with Lewis Basic Sites-Rich toward Charge-Exclusive Cationic Dyes Separation and Size-Selective Catalytic Reaction.

Organic dye pollutants become a big headache due to their toxic nature to the environment, and it should be one of the best solutions if we can separate and reuse them. Here, we report the synthesis and characterization of a microporous anion metal-organic framework (MOF) with Lewis basic sites-rich based on TDPAT (2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) ligand, FJI-C2, which shows high adsorption and separation of cationic dye based on the charge-exclusive effect. Compared to other MOF materials, FJI-C2 shows the largest adsorption amount of methylene blue (1323 mg/g) at room temperature due to the nature of the anion frameworks and high surface area/pore volume. Furthermore, motivated by the adsorption properties of large guest molecules, we proceeded to investigate the catalytic behaviors of FJI-C2, not only because the large pore facilitates the mass transfer of guest molecules but also because the high density of Lewis basic sites can act as effective catalytic sites. As expected, FJI-C2 exhibits excellent catalytic performance for size-selective Knoevenagel condensation under mild conditions and can be reused several times without a significant decrease of the activity.

Strong electron donation induced differential nonradiative decay pathways for para and meta GFP chromophore analogues.

Z-E Isomerisation because of rotation around the exocyclic double bond (known as the τ-twist) and not any other internal conversion has been reported to be the major nonradiative decay channel for non-hydroxylic unconstrained para and meta GFP chromophore analogues. The equation Φf + 2ΦZE = 1 has been shown to hold well for both para and meta GFP chromophore analogues. If the above equation holds true, then upon reducing the extent of Z-E isomerisation (ΦZE), the fluorescence quantum yield (Φf) should increase. To probe the above proposition two sets of non-hydroxylic unconstrained para and meta GFP chromophore analogues were synthesized. Quite interestingly by introducing the strongly electron donating -NEt2 group to the benzenic moiety these para and meta GFP chromophore analogues were shown to exhibit differential optical behaviour w.r.t. the extent of the solvatochromic shift, Φf, ΦZE, and τf. For the first time it has been shown that the well accepted equation Φf + 2ΦZE = 1 does not hold at all for these non-hydroxylic unconstrained meta analogues. Although ΦZE has been shown to be <10%, Φf is much lower than the expected near unity value for these meta analogues. After detailed investigation into the nonradiative excited state decay channel, contrary to literature reports, energy gap law governed internal conversion and not Z-E isomerisation was shown to be the major nonradiative decay channel for these meta analogues. Two models are put forward to understand the differential optical behaviour of these para and meta GFP chromophore analogues. Support from X-ray crystal structures, NMR experiments, and computational calculations has also been provided.

Pharmaceutical co-crystals: A green way to enhance drug stability and solubility for improved therapeutic efficacy.

Pharmaceutical co-crystals have gained significant attention in recent years as a promising green and sustainable method for poorly soluble drugs to improve their solubility, stability, and bioavailability. In the drug development research field, it is an extremely useful technique as it does not require a large number of synthetic steps as well a minimum amount of solvent is utilized or sometimes without solvent. This review presents a comprehensive investigation into the design, synthesis, characterization, and evaluation of pharmaceutical co-crystals. The study focuses on exploring different strategies for co-crystal formation, including co-grinding, solvent evaporation, and liquid-assisted grinding. Various characterization techniques such as SCXRD, PXRD, FTIR, and DSC were employed to confirm the formation and structural features of the co-crystals. The article also highlights the significance of understanding the intermolecular interactions within co-crystals and their influence on physicochemical properties. Furthermore, the article discusses the potential applications of pharmaceutical co-crystals in enhancing drug solubility, dissolution rate, and oral bioavailability, leading to improved therapeutic efficacy. Overall, this review provides valuable insights into the design and development of pharmaceutical co-crystals, offering a promising avenue for overcoming the difficulties brought on by poorly soluble drugs.

Graphene-Like Hydrogen-Bonded Melamine-Cyanuric Acid Supramolecular Nanosheets as Pseudo-Porous Catalyst Support.

Behaving as structural protectors and electronic modulators, catalyst supports such as graphene derivatives are generally constructed by covalent bonds. Here, hydrogen-bonded ultrathin nanosheets are reported as a new type of catalyst support. Melamine (M) and cyanuric acid (CA) molecules self-assemble to form the graphite-like hydrogen-bonded co-crystal M-CA, which can be easily exfoliated by ultrasonic treatment to yield ultrathin nanosheets with thickness of ≈1.6 nm and high stability at pH = 0. The dynamic nanosheets form adaptive defects/pores in the synthetic process of CoP nanoparticles, giving embedded composite with high hydrogen evolution activity (overpotential of 66 mV at 10 mA cm-2 ) and stability. Computational calculations, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy unveil the electron modulation effects of the nanosheets. This pseudo-porous catalyst support also can be applied to other metal phosphides.

Outstanding drug loading capacity by water stable microporous MOF: a potential drug carrier.

A robust, highly water stable (up to 3 weeks), microporous MOF, [Zn8(O)2(CDDB)6(DMF)4(H2O)] {where CDDB = 4,4'-(9-H carbazole-3,6-diyl)dibenzoic acid}, was synthesized based on an open N-H site by a solvothermal process and exhibited an outstanding loading capacity (around 53.3 wt%) and satisfactory release capability (64.9% and 81.9%) for 5-fluorouracil, constituting a negligible cytotoxicity effect.

Microwave-assisted large scale synthesis of lanthanide metal-organic frameworks (Ln-MOFs), having a preferred conformation and photoluminescence properties.

Preparation of MOF on a large scale is a great challenge due to difficulties in reproducibility. A microwave synthesis procedure plays a major role in solving this problem. Moreover, achievement of the preferred conformation in the case of the flexible ligand is also an important factor as it affects the stability of the MOF. In this regard, lanthanides are suitable candidates due to their large size and coordination capabilities. A series of isostructural microporous lanthanide metal-organic frameworks (Ln-MOFs), formulated as [Ln (TTTPC)(NO2)2(Cl)]·(H2O)10 {Ln = La (1), Ce (2), Pr (3), Nd (4), Eu (5), Tb (6), Dy (7), Ho (8), Yb (9); H3TTTPC = 1,1',1''-tris(2,4,6-trimethylbenzene-1,3,5-triyl)-tris(methylene)-tris(pyridine-4-carboxylic acid)}, has been synthesized on a large scale via a microwave-assisted solvothermal reaction over 5 min. Otherwise, if a conventional solvothermal reaction is carried out at the same temperature, a much longer reaction time (2 days) and slow evaporation (5 days) are needed to produce the same compound in similar yield. Moreover, in these circumstances, conventional methods are useful only for small scale (10 mg) syntheses, but on using microwave-assisted synthesis, up to 2 g was obtained. Structural analysis reveals that the framework of the as-synthesized MOFs is a 6-connected network with point symbol (4(11)·6(4)), which is a subnet of a uninodal net having a new topology, sqc885. Thermal gravimetric analyses performed on as-synthesized MOFs reveal that the frameworks have moderate thermal stability. Gas sorption properties of 1 and 8 were studied by experimentally measuring nitrogen and hydrogen sorption isotherms. The luminescent properties of 5 and 6 were investigated and show characteristic emissions for Eu(3+) and Tb(3+) at room temperature.

Heterometallic cluster-based indium-organic frameworks.

With the help of the ligand-oriented method, we have successfully embedded independent copper-based units into the indium-organic framework system for the first time, in which the Cu4I4 clusters and In3O(CO2)6 clusters coexist. This heterometallic cluster-based framework has a large porosity with extra-open channels along the c-axis, and its sorption capacity has also been investigated.