The crystal structure of 2-oxo-2H-chromen-4-yl acetate, C11H8O4

C11H8O4, monoclinic, P21/c (no. 14), a = 4.5947(2) Å, b = 10.5414(3) Å, c = 19.1611(7) Å, β = 94.084(2)°, V = 925.70(6) Å3, Z = 4, Rgt(F) = 0.0376, wRref(F 2) = 0.1109,T = 200(2) K.CCDC no.: 190638

Photo-and thermoresponsive N-salicylideneaniline derivatives : solid-state studies and structural aspects

Electronic supplementary information (ESI) available. CCDC 1899401, 1902658, 1966932, 1989369, 1989398, 1989403, 2014911, 2014914, 2019418, 2049690, 2049691, 2062423, 2157376, 2156456–2156467 and 2191107–2191119. For ESI and crystallographic data in CIF or other electronic format see DOI: https://doi. org/10.1039/d1nj03056f.N-Salicylideneaniline (SA) and its derivatives are known to possess chromism upon exposure to external stimuli. Herein, we present mechanochemical synthesis of a series of photo-and thermoresponsive SA-derivatives and report on solid-state stabilisation of their tautomeric forms either by change in temperature or by photoirradiation. The influence of UV light on proton transfer between the enol-imine (EI) and keto-amine (KA) forms was investigated at λ1 = 254 and λ2 = 365 nm. Differential scanning calorimetry (DSC) measurements provided extra information on the thermodynamic relationship between the prototropic tautomers, and their exposition to liquid nitrogen, combined with variable temperature single-crystal X-ray diffraction (VT-SCXRD) and spectroscopic data, ascertained structural reasons for the intrinsic thermo-optical properties of the compounds. A series of structural determinations between 150 and 300 K further shed light on the thermomechanical behaviour exhibited by the thermoresponsive compounds. By virtue of calorimetry we were able to demonstrate proton transfer via the intramolecular O⋯N hydrogen bond over the temperature range 193–453 K. This present work demonstrates the importance of applying complementary analytical techniques and appropriate approaches for understanding the switching behaviour between the EI and KA forms. Furthermore, the assertion that it is predominantly the planarity (φ < 25°) that determines thermochromaticity is questioned.The National Research Foundation (NRF), South Africa and Rhodes University Research Council.http://rsc.li/njchj2023Chemistr

The crystal structure of 2-oxo-2H-chromen-4-yl acetate, C11H8O4

C11H8O4, monoclinic, P21/c (no. 14), a = 4.5947(2) Å, b = 10.5414(3) Å, c = 19.1611(7) Å, β = 94.084(2)°, V = 925.70(6) Å3, Z = 4, Rgt(F) = 0.0376, wRref(F 2) = 0.1109,T = 200(2) K.CCDC no.: 190638

Cation-/ligand-induced solvent-assisted transformations of Zn(II) and Cu(II) complexes featuring single-pocket multidentate chelating members

A new family of single-pocket metal complexes bearing O,N,O-tridentate and O,N-bidentate chelating members {Cu, 1b (P21/n); Ni, 1c (C2/c); Mn, 1d (I2/a); Cu, 2b; and Ni, 2c (both P21/c)}, starting from synthesized and fully characterized Zn(II) (1a; I2/a) and Cu(II) (2a; C2) precursors, were conveniently prepared via cation-induced solvent-assisted and ligand-induced solvent-assisted transformations. Herein, we show multistep solvent-assisted transformations from cis-1a → trans-1b → cis-1c → cis-1d, as well as all-trans 2a → 2b → 2c. All processes are one-way irreversible, as substantiated by thermodynamic aspects (enthalpies based on Gibbs free energies) derived from density functional theory calculations. On the other hand, complex 2a′ (C2/c; a polymorphic form of 2a) was obtained through a routine synthetic procedure. The compounds have been established by various spectroscopic techniques (infrared, UV−vis, ESI-MS, 1H, and 13C NMR), elemental analysis, and X-ray crystallography. Single-crystal X-ray studies reveal that complexes 1a−d exhibit a pseudo-octahedral geometry around each metal center, with 2a displaying a four-coordinate seesaw geometry Cu(II) sphere (Addison parameter; τ = 0.42), while 2a′ (τ = 0.00), 2b (τ = 0.00), and 2c (τ = 0.00) possess a perfect square-planar configuration around each metal center. Furthermore, distortion is stabilized by the presence of peripheral Odonor atoms from the bulky −OMe group, and by virtue of its size, increased bond lengths and angles are accommodated. Ligand substitution induced coordination geometry transformation from quasi-square-planar 2a to perfect square-planar 2b. Assessment of the metric parameter shows that the distances between the two Cu−Omethoxy are all largely positive due to Jahn−Teller distortion, indicating an unprecedented tetragonal bipyramidal geometry in 1b.The National Research Foundation (NRF, South Africa), Atlantic Philanthropies Scholarship and Rhodes University Research Council.http://pubs.acs.org/journal/cgdefuChemistryNon

Enhanced Catalytic Activity of a Copper(II) Metal–Organic Framework Constructed <i>via</i> Semireversible Single-Crystal-to-Single-Crystal Dehydration

Herein, we present a copper(II) metal–organic framework, [Cu2(btec)(OH2)4]·2H2O (1) [(btec)4– = 1,2,4,5-benzenetetracarboxylate], that undergoes single-crystal-to-single-crystal transformations into two anhydrous phases 2′ and 2″ with the chemical formula [Cu2(btec)], triggered by two-step dehydration at 403 and 433 K, respectively. After immersion in water for 3 days at room temperature, 2′ transformed into [Cu2(btec)(OH2)] (3), while both 2′ and 2″ took 1 week to revert to 1. Dynamic vapor sorption studies validated water-induced reversible structural transformations at 70% relative humidity (RH). According to single-crystal X-ray diffraction (SC-XRD), the local coordination geometry of the Cu2+ ion in 2′ changed from a saturated octahedron to a coordinatively unsaturated square-based pyramid in 3, manifested by changes in color and dimensionality. From a topological point of view, all of the scaffolds show a binodal (3,6)-connected kgd topology with the point symbol {43}2{46}. In addition, the materials were thoroughly characterized using routine spectroscopic data and various analytical techniques. The catalytic activity of the microporous materials in the liquid-phase oxidation of styrene in acetonitrile, using 30% (wt) H2O2 as the oxidant, was investigated. The excellent performance of the monohydrous phase 3 was shown to be superior to the pristine framework and the anhydrous counterparts, as evidenced by a good turnover number (TON) and turnover frequency (TOF) = 82.6 and 21.0 h–1, respectively. Within 4 h, the substrates were catalytically oxidized to the desired products with up to 67% conversion and 100% benzaldehyde selectivity. It is worth noting that the accessible active metal sites and higher surface area enhanced the catalytic properties of 3. Furthermore, the maintenance of catalytic efficiency over five cycles and reusability are illustrated and discussed in terms of the structural differences of the microporous frameworks. Thus, a preliminary reaction mechanism for the selective oxidation of styrene is proposed. This study not only provides a fascinating example of MOF chromism achieved by thermal activation and rehydration but also sheds some light on the relationship between pore-surface- or metal-engineered sites in MOFs and their heterogeneous catalytic performances

Enhanced Catalytic Activity of a Copper(II) Metal–Organic Framework Constructed <i>via</i> Semireversible Single-Crystal-to-Single-Crystal Dehydration

Herein, we present a copper(II) metal–organic framework, [Cu2(btec)(OH2)4]·2H2O (1) [(btec)4– = 1,2,4,5-benzenetetracarboxylate], that undergoes single-crystal-to-single-crystal transformations into two anhydrous phases 2′ and 2″ with the chemical formula [Cu2(btec)], triggered by two-step dehydration at 403 and 433 K, respectively. After immersion in water for 3 days at room temperature, 2′ transformed into [Cu2(btec)(OH2)] (3), while both 2′ and 2″ took 1 week to revert to 1. Dynamic vapor sorption studies validated water-induced reversible structural transformations at 70% relative humidity (RH). According to single-crystal X-ray diffraction (SC-XRD), the local coordination geometry of the Cu2+ ion in 2′ changed from a saturated octahedron to a coordinatively unsaturated square-based pyramid in 3, manifested by changes in color and dimensionality. From a topological point of view, all of the scaffolds show a binodal (3,6)-connected kgd topology with the point symbol {43}2{46}. In addition, the materials were thoroughly characterized using routine spectroscopic data and various analytical techniques. The catalytic activity of the microporous materials in the liquid-phase oxidation of styrene in acetonitrile, using 30% (wt) H2O2 as the oxidant, was investigated. The excellent performance of the monohydrous phase 3 was shown to be superior to the pristine framework and the anhydrous counterparts, as evidenced by a good turnover number (TON) and turnover frequency (TOF) = 82.6 and 21.0 h–1, respectively. Within 4 h, the substrates were catalytically oxidized to the desired products with up to 67% conversion and 100% benzaldehyde selectivity. It is worth noting that the accessible active metal sites and higher surface area enhanced the catalytic properties of 3. Furthermore, the maintenance of catalytic efficiency over five cycles and reusability are illustrated and discussed in terms of the structural differences of the microporous frameworks. Thus, a preliminary reaction mechanism for the selective oxidation of styrene is proposed. This study not only provides a fascinating example of MOF chromism achieved by thermal activation and rehydration but also sheds some light on the relationship between pore-surface- or metal-engineered sites in MOFs and their heterogeneous catalytic performances

Synthesis and crystal structure of hexaaquacopper(II) 2,5-dicarboxyterephthalate, C10H16O14Cu

C10H16O14${\text{C}}_{10}{\text{H}}_{16}{\text{O}}_{14}$Cu, monoclinic, I2/a (no. 15), a = 7.2407(3) Å, b = 9.7565(4) Å, c = 21.1814(10) Å, β = 93.913(2)°, V = 1492.85(11) Å3, Z = 4, Rgt${R}_{gt}$(F) = 0.0198, wRref$w{R}_{\mathit{ref}}$(F2) = 0.0509, T = 200 K

Enhanced Catalytic Activity of a Copper(II) Metal–Organic Framework Constructed <i>via</i> Semireversible Single-Crystal-to-Single-Crystal Dehydration

Herein, we present a copper(II) metal–organic framework, [Cu2(btec)(OH2)4]·2H2O (1) [(btec)4– = 1,2,4,5-benzenetetracarboxylate], that undergoes single-crystal-to-single-crystal transformations into two anhydrous phases 2′ and 2″ with the chemical formula [Cu2(btec)], triggered by two-step dehydration at 403 and 433 K, respectively. After immersion in water for 3 days at room temperature, 2′ transformed into [Cu2(btec)(OH2)] (3), while both 2′ and 2″ took 1 week to revert to 1. Dynamic vapor sorption studies validated water-induced reversible structural transformations at 70% relative humidity (RH). According to single-crystal X-ray diffraction (SC-XRD), the local coordination geometry of the Cu2+ ion in 2′ changed from a saturated octahedron to a coordinatively unsaturated square-based pyramid in 3, manifested by changes in color and dimensionality. From a topological point of view, all of the scaffolds show a binodal (3,6)-connected kgd topology with the point symbol {43}2{46}. In addition, the materials were thoroughly characterized using routine spectroscopic data and various analytical techniques. The catalytic activity of the microporous materials in the liquid-phase oxidation of styrene in acetonitrile, using 30% (wt) H2O2 as the oxidant, was investigated. The excellent performance of the monohydrous phase 3 was shown to be superior to the pristine framework and the anhydrous counterparts, as evidenced by a good turnover number (TON) and turnover frequency (TOF) = 82.6 and 21.0 h–1, respectively. Within 4 h, the substrates were catalytically oxidized to the desired products with up to 67% conversion and 100% benzaldehyde selectivity. It is worth noting that the accessible active metal sites and higher surface area enhanced the catalytic properties of 3. Furthermore, the maintenance of catalytic efficiency over five cycles and reusability are illustrated and discussed in terms of the structural differences of the microporous frameworks. Thus, a preliminary reaction mechanism for the selective oxidation of styrene is proposed. This study not only provides a fascinating example of MOF chromism achieved by thermal activation and rehydration but also sheds some light on the relationship between pore-surface- or metal-engineered sites in MOFs and their heterogeneous catalytic performances

Enhanced Catalytic Activity of a Copper(II) Metal–Organic Framework Constructed <i>via</i> Semireversible Single-Crystal-to-Single-Crystal Dehydration

Herein, we present a copper(II) metal–organic framework, [Cu2(btec)(OH2)4]·2H2O (1) [(btec)4– = 1,2,4,5-benzenetetracarboxylate], that undergoes single-crystal-to-single-crystal transformations into two anhydrous phases 2′ and 2″ with the chemical formula [Cu2(btec)], triggered by two-step dehydration at 403 and 433 K, respectively. After immersion in water for 3 days at room temperature, 2′ transformed into [Cu2(btec)(OH2)] (3), while both 2′ and 2″ took 1 week to revert to 1. Dynamic vapor sorption studies validated water-induced reversible structural transformations at 70% relative humidity (RH). According to single-crystal X-ray diffraction (SC-XRD), the local coordination geometry of the Cu2+ ion in 2′ changed from a saturated octahedron to a coordinatively unsaturated square-based pyramid in 3, manifested by changes in color and dimensionality. From a topological point of view, all of the scaffolds show a binodal (3,6)-connected kgd topology with the point symbol {43}2{46}. In addition, the materials were thoroughly characterized using routine spectroscopic data and various analytical techniques. The catalytic activity of the microporous materials in the liquid-phase oxidation of styrene in acetonitrile, using 30% (wt) H2O2 as the oxidant, was investigated. The excellent performance of the monohydrous phase 3 was shown to be superior to the pristine framework and the anhydrous counterparts, as evidenced by a good turnover number (TON) and turnover frequency (TOF) = 82.6 and 21.0 h–1, respectively. Within 4 h, the substrates were catalytically oxidized to the desired products with up to 67% conversion and 100% benzaldehyde selectivity. It is worth noting that the accessible active metal sites and higher surface area enhanced the catalytic properties of 3. Furthermore, the maintenance of catalytic efficiency over five cycles and reusability are illustrated and discussed in terms of the structural differences of the microporous frameworks. Thus, a preliminary reaction mechanism for the selective oxidation of styrene is proposed. This study not only provides a fascinating example of MOF chromism achieved by thermal activation and rehydration but also sheds some light on the relationship between pore-surface- or metal-engineered sites in MOFs and their heterogeneous catalytic performances

Enhanced Catalytic Activity of a Copper(II) Metal–Organic Framework Constructed <i>via</i> Semireversible Single-Crystal-to-Single-Crystal Dehydration

Herein, we present a copper(II) metal–organic framework, [Cu2(btec)(OH2)4]·2H2O (1) [(btec)4– = 1,2,4,5-benzenetetracarboxylate], that undergoes single-crystal-to-single-crystal transformations into two anhydrous phases 2′ and 2″ with the chemical formula [Cu2(btec)], triggered by two-step dehydration at 403 and 433 K, respectively. After immersion in water for 3 days at room temperature, 2′ transformed into [Cu2(btec)(OH2)] (3), while both 2′ and 2″ took 1 week to revert to 1. Dynamic vapor sorption studies validated water-induced reversible structural transformations at 70% relative humidity (RH). According to single-crystal X-ray diffraction (SC-XRD), the local coordination geometry of the Cu2+ ion in 2′ changed from a saturated octahedron to a coordinatively unsaturated square-based pyramid in 3, manifested by changes in color and dimensionality. From a topological point of view, all of the scaffolds show a binodal (3,6)-connected kgd topology with the point symbol {43}2{46}. In addition, the materials were thoroughly characterized using routine spectroscopic data and various analytical techniques. The catalytic activity of the microporous materials in the liquid-phase oxidation of styrene in acetonitrile, using 30% (wt) H2O2 as the oxidant, was investigated. The excellent performance of the monohydrous phase 3 was shown to be superior to the pristine framework and the anhydrous counterparts, as evidenced by a good turnover number (TON) and turnover frequency (TOF) = 82.6 and 21.0 h–1, respectively. Within 4 h, the substrates were catalytically oxidized to the desired products with up to 67% conversion and 100% benzaldehyde selectivity. It is worth noting that the accessible active metal sites and higher surface area enhanced the catalytic properties of 3. Furthermore, the maintenance of catalytic efficiency over five cycles and reusability are illustrated and discussed in terms of the structural differences of the microporous frameworks. Thus, a preliminary reaction mechanism for the selective oxidation of styrene is proposed. This study not only provides a fascinating example of MOF chromism achieved by thermal activation and rehydration but also sheds some light on the relationship between pore-surface- or metal-engineered sites in MOFs and their heterogeneous catalytic performances