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External-stimuli responsiveness as found in natural organisms and smart materials is attractive for functional materials scientists who attempt to design and imitate fascinating behavior into their materials. Herein, we report a couple of new solvent-responsive isostructural two-dimensional cationic metal–organic frameworks (MOFs) of Mn(II) (1a) and Zn(II) (2a) that undergo unprecedented single-crystal to single-crystal (SCSC) transformation toward the corresponding isostructural three-dimensional MOFs of Mn(II) (1b) and Zn(II) (2b). The 2D MOFs 1aand 2ahave been effortlessly and rapidly synthesized via the microwave-heating technique. The SCSC transformations are synergistically induced by solvent and ligand-substitution reactions and able to be triggered by water, methanol, ethanol, and n-propanol. Time-dependent SCSC transformations were studied by in situ X-ray diffraction. Investigations on photodegradation of methyl orange showed that Zn-MOF 2bhas higher efficiency than Mn-MOF 1bunder UV–C irradiation at 300 min, 94.27%, and 21.91%, respectively. The influence of charge on the dye molecules, heterogeneity of the catalysis, and •OH radical-scavenging test was studied. First-principles computations suggest that the high photocatalytic activity of 2bmay be attributed to its suitable band-edge position for redox reactions.

A new cationic rectangular zinc(II) metal–organic framework (MOF) containing flexible chainlike bridging glutarate (glu) and rigid rodlike 4,4′-bipyridine (4,4′-bipy) ligands with an encapsulated perchlorate counteranion, {[Zn3(4,4′-bipy)4(glu)2](ClO4)2}n(1; P1̅), was studied. Complex 1has been successfully synthesized from the zinc(II) perchlorate salt by using microwave-heating techniques. In the crystal structure of 1, 4,4′-bipy ligands link trinuclear octahedral Zn(II) building units into rectanglular two-dimensional sheets. The glu2–ligands with anti–anticonformation expand the structure into a cationic rectangular 3D MOF with two crystallographically related perchlorate (ClO4–) counteranions encapsulated in a rectangular {Zn3(4,4′-bipy)4(glu)2}2+structure as a template of the structure. X-ray diffraction revealed the octahedral to tetrahedral (Znoct–Zntet) conversion upon a ligand-substitution-induced single-crystal to single-crystal (SCSC) transformation of the octahedral ZnoctMOF 1(P1̅); triggering by chloride led to a the 1D-zigzag chain [Zntet(4,4′-bipy)Cl2]n(2; C2/c), triggering by bromide led to a mixed crystalline phase between the isostructural 1D-zigzag chain [Zntet(4,4′-bipy)Br2]n(3;C2/c) and its polymorph, [Zntet(4,4′-bipy)Br2]n(4; P212121), and triggering by iodide led to a 3D-framework [Zntet(glu)]n(5; P21/c). The time-dependent bromide-triggered SCSC transformation was revealed by X-ray diffraction. Photocatalysis for methyl orange degradation of 1showed that the degradation efficiency reached 14.15% within 300 min under UV-C irradiation.

An anion-controlled synthesis of a new three-dimensional (3D) “racemate”, an enantiomorphic twofold interpenetrated 3D zinc(II) coordination polymer containing bridging glutarate (glu) and 4,4′-bipyridine (4,4′-bipy) ligands, {[Zn4(H2O)2(4,4′-bipy)4(glu)3](NO3)2}n, 1(P21/c), with ligand substitution-induced single-crystal-to-single-crystal (SCSC) transformation and photocatalysis for dye degradation was studied. The influence of a counteranion in zinc(II) starting materials and synthetic techniques upon the phase formation were explored. The complex 1was successfully synthesized from zinc(II) nitrate salt via microwave-assisted techniques as well as the conventional hydrothermal technique, whereas the employment of zinc(II) acetate or sulfate salt yielded a two-dimensional coordination polymer, [Zn(4,4′-bipy)(glu)]n, 2(P1̅), and the use of zinc(II) chloride led to a one-dimensional (1D) zigzag chain, [Zn(4,4′-bipy)Cl2]n3(C2/c). The synthetic-method-dependent formation was illustrated as the microwave-assisted techniques and conventional hydrothermal technique enabled the formation of crystalline-phase pure 1, while the sonochemical synthesis provided mixed crystalline-phases of 1and 2. In the structure of 1, the 4,4′-bipy ligand links dinuclear Zn(II) building units into 1D chains along the [1̅01] direction. The glu2–ligand acts as tethering linkers expanding the structure into a cationic 3D coordination polymer that interpenetrates with its enantiomer to give a 3D solid-state “racemate”. Powder X-ray diffraction revealed that the ligand substitution-induced SCSC transformation of the twofold interpenetrated 3D framework, 1(P21/c), which was triggered by chloride, led to a 1D zigzag chain, 3(C2/c), whereas the bromide-triggered reaction led to a mixed crystalline phase between the isostructural 1D zigzag chain, [Zn(4,4′-bipy)Br2]n, 4(C2/c), and its polymorph, [Zn(4,4′-bipy)Br2]n, 5(P212121). The photocatalysis for the methyl orange degradation of 1was studied.

An atom- and step-economic synthesis of aryliminophosphoranes bearing orthourea was achieved via unprecedented Ph3P-I2mediated ring-opening of 1,3-dihydro-1H-benzimidazol-2-ones with secondary amines. Tandem aza-Wittig/heterocyclization of the functionalized aryliminophosphoranes upon treatment with isothiocyanates enables a facile access to a single regioisomer of N1-substituted 2-aminobenzimidazoles as well as fused tetracyclic quinazolinone derivatives in one-pot. 31P{1H} NMR studies suggested that the urea C–N bond of benzimidazolone is weakened by N-phosphorylation, leading to aminolysis rather than the expected deoxygenative amination.

Instead of the expected substituted 2-aminobenzo[d]oxazoles, relatively stable ring-opened oxyphosphonium betaines were isolated for the first time from the Ph3P–I2-mediated reactions of benzo[d]oxazol-2(3H)-ones with acyclic secondary amines. The structure of one of these compounds was unambiguously confirmed by single-crystal X-ray analysis. Thermolysis of the betaines gave rise to 2-dialkylaminobenzoxazoles with concomitant loss of triphenylphosphine oxide, suggesting their possible role as intermediates in an alternative reaction path.

The first phytochemical investigation of the twig extract of Uvaria leptopodaresulted in the isolation and identification of three new tetrahydroxanthene-1,3(2H)-diones, uvarialeptones A–C, two new oxidized hexadiene derivatives, uvarialeptols A and B, together with ten known compounds. Their structures were elucidated by spectroscopic techniques and mass spectrometry. Uvarialeptones A and B were unprecedented tetrahydroxanthene-1,3(2H)-dione dimers which exhibited a cyclobutane ring via [2 + 2] cycloaddition from uvarialeptone C and 9a-O-methyloxymitrone, respectively. The structure of uvarialeptone A was confirmed by X-ray diffraction analysis using Mo Kα radiation. Compound 3inhibited NO production at an IC50value of 6.7 ± 0.1 μM.

The performance of the one-dimensional (1D) morphology as an inorganic UV filter for sunscreens of titanium dioxide (TiO2) was evaluated in this research. The 1D TiO2nanowires were prepared using solid TiO2and 10 M NaOH as precursors via a modified hydrothermal method, followed by calcination at 400–900°C for 5 h. The influences of TiO2loading, hydrothermal time and calcination temperature were studied on the morphologies of the as-prepared samples. The morphologies of the TiO2nanowires were investigated using SEM and TEM techniques. The results found all the variables directly affected the particle size and shape of the TiO2nanowires. The hydrothermal synthesis conditions using a TiO2loading of 0.2 g at 220°C for 24 h (HTiO2) resulted in a particle size that was the longest and narrowest in length and diameter, respectively. The first product from the hydrothermal synthesis is H2Ti3O7, which can transform into TiO2(B) (TiO2@400), anatase (TiO2@700) and rutile (TiO2@900) by calcination at 400, 700 and 900 °C, respectively. The calcined samples were selected for a porcine skin penetration study. The 1D morphology particles were localized on the stratum corneum of the skin, while the comparison spherical particle penetrated the deeper layer. From the SPF test, the highest SPF is TiO2anatase.

Fabrication of a new three-dimensional Cu(II) metal–organic framework, {[Cu4(4,4′-bipy)3(OH)2(mal)3]·4H2O}n(1a; 4,4′-bipy = 4,4′-bipyridine, H2mal = malonic acid; P21/m), that undergoes an unprecedented redox-versatile ligand-substitution-induced single-crystal to single-crystal transformation, for smartphone-based detection of iodide was studied. The Cu-MOF 1ahas been effortlessly synthesized by the microwave-heating technique. Phase formation of the Cu-MOF 1adepended on counter-anions. The transformations can be triggered by halides to corresponding coordination polymers through both non-redox and redox-associated pathways. The changes in the local structure and oxidation state of copper during the transformation were studied by ex situ and in situ synchrotron X-ray absorption spectroscopies. The selectivity of the halide-triggered transformation was investigated. A study on smartphone-based colorimetric detection of iodide was found to be linearly proportional to the iodide concentration in the range 10–1500 mg/L with a limit of detection of 5 mg/L and good precision relative standard deviation of 1.9% (n= 11), possibly to construct the iodide test kit.