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The random lamellae of the synthetic CP were synthesized with a hydrothermal approach using o-Phenylenediamine (OPD) as a modifier. The decreases in the order degree of the CP synthesized in the presence of the OPD resulted from the loss of long-range order in a certain direction. Subsequently, the ultrasonic treatment and washing were conducive to further facilitate the disordered arrangements of its lamellae. The possible promotion mechanism regarding the nucleation and growth behaviors of the sol-gel particles was proposed. The fractal evolutions of the aluminosilicate species with crystallization time implied that the aluminosilicate species became gradually smooth to rough during the crystallization procedures since the amorphous structures transformed into flower-like morphologies. Their gas adsorption and separation performances indicated that the adsorption capacity of CO2 at 273 K reached up to 2.14 mmol·g−1 at 1 bar, and the selective factor (CO2/CH4) up to 3.4, much higher than that of the CPs synthesized without additive OPD. The breakthrough experiments displayed a longer breakthrough time and enhancement of CO2 uptake, showing better performance for CO2/CH4 separation. The cycling test further highlighted their efficiency for CO2/CH4 separation. [ABSTRACT FROM AUTHOR]

Developing effective intelligent nanocarriers is highly desirable for fluorescence imaging and therapeutic applications but remains challenging. Using a vinyl-grafted BMMs (bimodal mesoporous SiO2 materials) as a core and PAN ((2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione))-dispersed dual pH/thermal-sensitive poly(N-isopropylacrylamide-co-acrylic acid) as a shell, PAN@BMMs with strong fluorescence and good dispersibility were prepared. Their mesoporous features and physicochemical properties were extensively characterized via XRD patterns, N2 adsorption–desorption analysis, SEM/TEM images, TGA profiles, and FT-IR spectra. In particular, their mass fractal dimension (dm) features based on SAXS patterns combined with fluorescence spectra were successfully obtained to evaluate the uniformity of the fluorescence dispersions, showing that the dm values increased from 2.49 to 2.70 with an increase of the AN-additive amount from 0.05 to 1%, along with the red shifting of their fluorescent emission wavelength from 471 to 488 nm. The composite (PAN@BMMs-I-0.1) presented a densification trend and a slight decrease in peak (490 nm) intensity during the shrinking process. Its fluorescent decay profiles confirmed two fluorescence lifetimes of 3.59 and 10.62 ns. The low cytotoxicity obtained via in vitro cell survival assay and the efficient green imaging performed via HeLa cell internalization suggested that the smart PAN@BMM composites are potential carriers for in vivo imaging and therapy. [ABSTRACT FROM AUTHOR]

Various cation–exchanged clinoptilolites (M–CPs, M = Li+, Cs+, Ca2+, Sr2+) were prepared, and their exchanged thermodynamic (and kinetic) properties and adsorption performances for CH4, N2, and CO2 were investigated. The results demonstrated that the relative crystallinity of M–CPS decreased with the increase of exchange times. Their chemisorbed water weight loss gradually increased with the increasing exchange times, except that of Cs–x–CP. The Δr G m θ values of exchange process of Li+, Cs+, Ca2+, or Sr2 presented the increased trend with the enhanced exchange times, but they decreased as the temperature increased. The negative Δr G m θ values and the positive Δr H m θ and Δr S m θ values suggested that the exchanged procedure belonged to spontaneous, endothermic, and entropy-increasing behaviors; their kinetic performances followed a pseudo–second–order model. However, the calculated Ea values of exchange process showed the increased tendencies with the enhanced exchange times, indicating that the exchange process became more difficult. Finally, the preliminary adsorption results indicated that the maximum adsorption amount at 273 K and 1 bar was 0.51 mmol/g of CH4 and 0.38 mmol/g of N2 by (Na, K)–CP, and 2.32 mmol/g of CO2 by Li–6–CP. [ABSTRACT FROM AUTHOR]

The three bipyridine‐proline chiral ligands (Z) with different structural units as highly active species were successfully introduced on Zn‐modified bimodal mesoporous silicas (BMMs). The representative heterogeneous catalysts (ZZnBMMs‐n) containing different molar ratios of Z/Zn (5, 20, 50, 100, 200%) were prepared, and their catalytic performances were evaluated in the asymmetric aldol reactions between p‐nitrobenzaldehyde and cyclohexanone, showing the satisfactory activities (yields) and good stereoselectivity (dr and ee). Meanwhile, their microstructural features and physicochemical properties were characterized by various methods. Particularly, the fractal evolution, the pair distance distribution function, and the Porod plots of the ZZnBMMs catalysts were demonstrated by SAXS analysis. The results revealed that the interfacial layer thickness and their mass fractal (Dm) value gradually increased with the enhanced molar ratios of Z/Zn, along with the decrease of pore size and densification of volume, suggesting the successful Z‐grafting into the mesoporous channels of Zn‐modified matrixes. The essential relationships between the fractal features and their catalytic performance (yield, dr and ee) were explored, showing the larger the Dm values, the better catalytic performance. Besides, the uniform distributions of Zn and S elements in ZZnBMMs catalysts and the formation of enamine‐imine intermediates during the asymmetric aldol reactions were confirmed. [ABSTRACT FROM AUTHOR]

Titanates are frequently used as precursors to prepare transesterification catalysts with TiIV species. Unfortunately, it is challenging to control the dispersity of TiIV active sites on supports. Herein, a series of TiIV species is anchored on abundant linker vacancy sites by introducing point and large scale defects in UiO-66(Zr/Ti) with hierarchical-pore structure. The catalyst functionalized by titanium(IV) oxide bis(2,4-pentanedionate) shows excellent catalytic performance in the transesterification of dimethyl carbonate with phenyl acetate. The catalysts are characterized by XRD, FT-IR, N2 adsorption–desorption, XPS, SEM and STEM-HAADF techniques. The results demonstrate that the delicate mesopores in the support can not only exhibit a large surface area for the distribution of the active sites, but also provide better mass transfer performance. Meanwhile, the introduction of octahedral TiIV ions raises the activity of the catalyst via more coordinatively unsaturated ZrIV sites. Furthermore, using titanium(IV) oxide bis(2,4-pentanedionate) as a Ti source can effectively prevent the condensation of tetrahedral TiIV species anchored on the hierarchical-pore UiO-66(Zr/Ti) support. [ABSTRACT FROM AUTHOR]

The catalysts containing tetra-coordinated titanium have been widely used for transesterification. The key issue in the design of these catalysts is the stability of tetra-coordinated titanium. In this study, mesoporous amorphous titanium oxides coated on a zeolitic imidazolate framework (ZIF-8) were developed by using a hexadecylamine (HDA) surfactant as a structure-directing agent. The mesopores surface areas of the amorphous TiO2 shell could be simply controlled by changing the dosage of HDA in the synthetic process. The novel, efficient and recyclable heterogeneous catalyst was introduced to the synthesis of diphenyl carbonate from dimethyl carbonate and phenyl acetate for the first time. The catalyst structure was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption, Fourier transform infrared spectroscopy and thermogravimetric analysis. The effects of the molar ratio of Ti to Zn, HDA amount, catalyst amount, reaction time and reusability on the yield of the transesterification products were also determined. The results showed that the mesopores of TiO2 shell facilitated reactants and productions diffusion to increase the conversion of phenyl acetate and yield of diphenyl carbonate. Moreover, the coordination between titanium and ZIF-8 also endowed the catalysts with reasonable reusability. [ABSTRACT FROM AUTHOR]

Using poly(acrylic acid) (abbreviated as PAA) as a shell, bimodal mesoporous silicas (abbreviated as BMMs) as a core, and bipyridine-proline (abbreviated as Z) as an active species, a facile approach for preparation of the P-Z@BMMs nanocomposites with core–shell structure was proposed, which was used as a suitable pH-sensitive catalyst for asymmetric aldol reaction between p-nitrobenzaldehyde and cyclohexanone. Their microstructural features and physicochemical properties were extensively characterized by various methods, such as powder X-ray diffraction patterns, N 2 adsorption–desorption isotherms, the scanning (and transmission) electron microscopy images, the dynamic light scattering measurements, the thermogravimetric analysis, the elemental analysis, and the Fourier transform infrared spectroscopy spectra. Particularly, their fractal evolution, the pair distance distribution function, and the Porod plots were demonstrated via the small-angle X-ray scattering patterns. The results elucidated that the PAA was successfully incorporated onto the external amino-modified surfaces of the mesoporous BMMs, and the particles having PAA grafted thereon had a pH-responsive shell in thickness of around 0.97 nm for controlled release of Z species by adjusting pH value of the reaction medium. Besides, the synthesized P-Z@BMMs presented the satisfactory catalytic yields (around 80%) in comparison with the homo- and heterogeneous catalytic system using Z or Z@BMMs as the catalysts. [ABSTRACT FROM AUTHOR]

Cover Feature: Fractal Features of the Catalytic Performances of Bimodal Mesoporous Silica-Supported Organocatalysts Derived from Bipyridine-Proline for Asymmetric Aldol Reaction (Asian J. Org. Keywords: Bimodal mesoporous silicas; Bipyridine-proline; Small-angle X-ray scattering; Fractal feature; Asymmetric aldol reaction EN Bimodal mesoporous silicas Bipyridine-proline Small-angle X-ray scattering Fractal feature Asymmetric aldol reaction 1 1 1 02/21/22 20220201 NES 220201 B Heterogeneous catalysis b is a promising way to developing benign processes in asymmetric aldol reaction, in which the catalytic performance can be precisely modulated by bipyridine-proline loaded catalyst. Bimodal mesoporous silicas, Bipyridine-proline, Small-angle X-ray scattering, Fractal feature, Asymmetric aldol reaction. [Extracted from the article]

Clinoptilolite (CP) with various morphologies, such as spherical, flower, cylindrical, and disc-shape, were successfully synthesized in the presence of alcohol solvents with different carbon chain lengths. The structural and textural properties of the resultant CPs were characterized via XRD, SEM, TG-DSC profiles, TEM, NMR, FT-IR spectra, and N 2 sorption isotherms. The effect of the additive amount of various alcohol solvents on the induction (nucleation) periods and growth stages of synthetic CPs were detailed investigated. Their activation energies of induction (E n) and growth (E g) periods during crystallization intervals were calculated according to the Arrhenius equation, where the former being larger than the latter, indicating that nucleation is the key step during the whole synthesis of CPs. Particularly, the E n value gradually increased as the increasing chain-length of the used alcohol, but smaller than that without additive alcohols. These demonstrations implied that the presence of alcohol solvents is beneficial to promote the nucleation process of synthetic CP. Furthermore, their CH 4 and N 2 adsorption capacity and selectivity were preliminary explored, showing the highest selective factor of 5.58 at 0 °C for CH 4 /N 2 separation using flower-like CP as an adsorbent. These results suggested a promising adsorbent for wide applications in gas separation. [Display omitted] • Alcohol-modified hydrothermal method for synthesis of clinoptilolite was proposed. • Influence of aliphatic alcohols on morphology of clinoptilolites was explored. • Crystalline kinetic for induction and growth stage in clinoptilolite was studied. • Application of synthetic clinoptilolite in CH 4 /N 2 separation was investigated. [ABSTRACT FROM AUTHOR]

The amine (NH 2 )-functionalized UiO-66 was successfully anchored on disorderly layered clinoptilolite (CP) via surfactant (poly(ethylene glycol) (PEG) and poly(vinylpyrrolidone) (PVP))-assisted induction. The structural features and physicochemical parameters of the resultant UiO-66-on-CPs were characterized by powder X-ray diffraction (XRD) patterns, scanning/transmission electron microscopy (SEM/TEM) images, Fourier transform infrared (FT-IR) spectra, N 2 sorption isotherms, and small-angle X-ray scattering (SAXS) patterns. The results demonstrated that the growth of UiO-66-NH 2 nanoparticles facilitated the disorder degree of the crystal plane of CP along the a-axis, while the addition of PEG in the hydrothermal synthesis system of CP was conducive to the formation of a flower-like microstructure and the introduction of PVP was beneficial to the nucleation and growth of UiO-66-NH 2 nanoparticles with a small size (40 nm) on the surfaces of the obtained CP-PEG lamellas. Finally, the gas-selective adsorption and separation performances of CO 2 and CH 4 were evaluated using the synthesized disorderly layered UiO-66-on-CP heterostructures as adsorbents, indicating that the NH 2 -functionalized UiO-66-on-CP exhibited a superior selective factor (3.66) of CO 2 /CH 4 . These results elucidated that the proposed approach is a promising strategy for constructing MOF-on-zeolite heterostructures, which may open an avenue to expand CP application and improve their performance.

Nanoprecursors used as a structural promoter (SP) were prepared by a hydrothermal method and named sol-SP. After centrifugation, the supernatant and precipitate were denoted as solution-SP and solid-SP, respectively. The effect of the additive amount on the structures and properties of the synthesized clinoptilolite was investigated using various characterization techniques. The activation energies of crystallization kinetics during induction and growth periods were calculated. The results showed that the induction period is the control step during the synthesis of clinoptilolite, while additive sol-SP or solid-SP was beneficial to shorten the induction period and therefore enhance the formation of the crystal nucleus. When their pre-crystallization time was too long or the additive amount was too much, the impure phase (phillipsite) in the synthesized clinoptilolite was easily generated. Although the addition of solution-SP had no obvious effect on the induction period, it promoted the growth of crystals after nucleation. Finally, the adsorption performances for CO 2 and CH 4 were preliminarily assessed using synthetic clinoptilolite as the adsorbent, showing the promising application for the separation of CO 2 /CH 4 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)