Polymorphism and Its Influence on Catalytic Activities of Lanthanide-Glutamate-Oxalate Coordination Polymers.

To study the relationship between polymorphism and catalytic activities of lanthanide coordination polymers in the cycloaddition reactions of CO2 with epoxides, the monoclinic and triclinic polymorphs of [LnIII(NH3-Glu)(ox)]·2H2O, where LnIII = LaIII (I), PrIII (II), NdIII (III), SmIII (IV), EuIII (V), GdIII (VI), TbIII (VII), and DyIII (VIII), NH3-Glu- = NH3+ containing glutamate, and ox2- = oxalate, were synthesized and characterized. Factors determining polymorphic preference, the discrepancy between the two polymorphic framework structures, potential acidic and basic sites, thermal and chemical stabilities, active surface areas, void volumes, CO2 sorption/desorption isotherms, and temperature-programmed desorption of NH3 and CO2 are comparatively presented. Based on the cycloaddition of CO2 with epichlorohydrin in the presence of tetrabutylammonium bromide under solvent-free conditions and ambient pressure, catalytic activities of the two polymorphs were evaluated, and the relationship between polymorphism and catalytic performances has been established. Better performances of the monoclinic catalysts have been revealed and rationalized. In addition, the scope of monosubstituted epoxides was experimented and the outstanding performance of the monoclinic catalyst in the cycloaddition reaction of CO2 with allyl glycidyl ether under ambient pressure has been disclosed.

Postsynthetic Installation of Lanthanide Cubane Clusters in a 3D Hydrogen-Bonded Framework of IrIII4ZnII4 Multicarboxylates.

Immersing single crystals of (Δ)4-K6[Ir4Zn4O(l-cysteinate)12]·nH2O (K6[1Ir]·nH2O) bearing 12 free carboxylate groups, which was newly prepared from Δ-H3[Ir(l-cysteinate)3], ZnBr2, ZnO, and KOH, in an aqueous solution of lanthanide(III) acetate produced Ln2[1Ir]·nH2O (2Ln; Ln = LaIII, CeIII, PrIII, and NdIII) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1Ir]·nH2O (3Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII, ErIII, HoIII, TmIII, YbIII, and LuIII) in a single-crystal-to-single-crystal transformation manner. X-ray crystallography showed that the KI ions in K6[1Ir]·nH2O are completely exchanged by the LnIII ions in 2Ln and 3Ln, retaining the 3D hydrogen-bonded framework that consists of the IrIII4ZnII4 complex anions of [1Ir]6-. While 2Ln contained the LnIII ions as isolated aqua species, the LnIII ions in 3Ln existed as cationic cubane clusters of [Ln4(OH)4(OAc)3(H2O)7]5+; these were linked by [1Ir]6- anions through carboxylate groups in a 3D polymeric structure. 3Ln showed magnetic and photoluminescence properties that are characteristically observed for discrete LnIII species in the solid state.

Crystal structure and characterization of a new lanthanide coordination polymer, [Pr2(pydc)(phth)2(H2O)3]·H2O.

A new lanthanide coordination polymer, poly[[tri-aqua-bis-(µ4-phthalato)(µ3-pyridine-2,5-di-carboxyl-ato)dipraseodymium] monohydrate], {[Pr2(C7H3NO4)2(C8H4O4)(H2O)3]·H2O}n or {[Pr2(phth)2(pydc)(H2O)3]·H2O}n, (pydc2- = pyridine-2,5-di-carboxyl-ate and phth2- = phthalate) was synthesized and characterized, revealing the structure to be an assembly of di-periodic {Pr2(pydc)(phth)2(H2O)3}n layers. Each layer is built up by edge-sharing {Pr2N2O14} and {Pr2O16} dimers, which are connected through a new coordin-ation mode of pydc2- and phth2-. These layers are stabilized by inter-nal hydrogen bonds and π-π inter-actions. In addition, a three-dimensional supra-molecular framework is built by inter-layer hydrogen-bonding inter-actions involving the non-coordinated water mol-ecule. Thermogravimetric analysis shows that the title compound is thermally stable up to 400°C.

Base-Directed Formation of Isostructural Lanthanide-Sulfate-Glutarate Coordination Polymers with Photoluminescence.

A series of five isostructural 3D lanthanide-based coordination polymers [LnIII2(H2O)6(glu)(SO4)2]n [Ln = Pr(1), Nd(2), Sm(3), Eu(4), and Gd(5)] was effortlessly obtained within a few minutes via the microwave-heating method. The employment of auxiliary bases, that is, sodium hydroxide, 4,4'-bipyridine, and 1,4-diazabicyclo[2.2.2]octane, led to the formation of the title complex, whereas base-free synthesis yielded a three-dimensional inorganic coordination polymer, [Ln2(H2O)4(SO4)3]n·nH2O, Ln = Nd (2a). The robustness of the synthetic method was illustrated as both microwave-heating and conventional hydrothermal techniques also enabled the formation of a high-crystalline phase-pure complex 1-5. In the structure of 1-5, glutarato (glu2-) and sulfato ligands link dinuclear Ln(III) building units into three-dimensional frames. The glu2- ligands act as tethering linkers, expanding the structure into a neutral 3D coordination network. Hydrogen bonds were found to be the predominant intermolecular interactions in the crystal structures. Photoluminescence of the complex 1-5 was studied.

Ecofriendly alkali metal cations diffusion improves fabrication of mixed-phase titania polymorphs on fixed substrate by chemical vapor deposition (CVD) for photocatalytic degradation of azo dye.

Controlling the nanoscale synthesis of semiconductor TiO2 on a fixed substrate has fascinated the curiosity of academics for decades. Synthesis development is required to give an easy-to-control technique and parameters for TiO2 manufacture, leading to advancements in prospective applications such as photocatalysts. This study, mixed-phase TiO2(B)/other titania thin films were synthesized on a fused quartz substrate utilizing a modified Chemical vapor depodition involving alkali-metal ions (Li+, Na+, and K+) solution pre-treatment. It was discovered that different cations promote dramatically varied phases and compositions of thin films. The films had a columnar structure with agglomerated irregular-shaped particles with a mean thickness of 800-2000 nm. Na+ ions can promote TiO2(B) more effectively than K+ ions, however Li+ ions cannot synthesize TiO2(B). The amounts of TiO2(B) in thin films increase with increasing alkali metal (K+ and Na+) concentration. According to experimental and DFT calculations, the hypothesized TiO2(B) production mechanism happened via the meta-stable intermediate alkaline titanate transformation caused by alkali-metal ion diffusion. The mixed phase of TiO2(B) and anatase TiO2 on the fixed substrate (1 × 1 cm2) obtained from Na+ pre-treated procedures showed significant photocatalytic activity for the degradation of methylene blue. K2Ti6O12, Li2TiO3, Rutile TiO2, and Brookite TiO2 phase formations produced by K+ and Li + pretreatment are low activity photocatalysts. Photocatalytic activities were more prevalent in NaOH pre-treated samples (59.1% dye degradation) than in LiOH and KOH pre-treated samples (49.6% and 34.2%, respectively). This revealed that our developed CVD might generate good photocatalytic thin films of mixed-phase TiO2(B)/anatase TiO2 on any substrate, accelerating progress in future applications.

Reversible Structural Transformation and Catalytic Potential of Lanthanide-Azobenzenetetracarboxylates.

Inspired by the catalytic potential of lanthanide coordination polymers of 3,3',5,5'-azobenzenetetracarboxylic acid (H4abtc), two new isostructural [Ln2III(Habtc)2(DMSO)4]·DMSO·H2O (LnIII = SmIII (I), EuIII = (II), DMSO = dimethyl sulfoxide) were synthesized and characterized. Their single-crystal structures were elucidated and described. Structural transformations of II in the solid state prompted by ligand substitution and thermal treatment were studied, from which genuine reversible transformation of II to [EuIII(Habtc)(H2O)4]·3H2O (II') and [EuIII(Habtc)(H2O)2]·2H2O (II″) was revealed. This illustrates the rare case of reversible transformation in lanthanide coordination polymers. The transformation between II' and II″ was also investigated. Structural transformations among these frameworks are discussed with regard to the coordination environment of EuIII, coordination modes of Habtc3-, and similarities and disparities in framework architecture and registration. In addition, the catalytic performance of II with and without the prior activation in CO2 cycloaddition reaction with epichlorohydrin was studied in comparison with II' and II″. The excellent performance of II disregarding the activation process has been demonstrated with the maximum turnover number and turnover frequency of 7682 and 1921 h-1, respectively, for the activated II and 7142 and 1786 h-1, respectively, for the nonactivated II. The maintenance of the catalytic efficiency over 10 cycles of the catalysis and the regeneration process is illustrated and discussed with respect to structural transformation.

Mercury removal efficiency of disulfide- and thiol-functionalized lanthanide coordination polymers.

To compare efficiency of disulfide and thiol groups in removing mercury from aqueous medium without noteworthy influence from structural differences, a series of new [LnIII(dtba)1.5(H2O)2] (LnIII = EuIII (I), GdIII (II) and TbIII (III), H2dtba = 4,4'-dithiobenzoic acid) were synthesized and characterized. The single crystal structure of I was elucidated and is described. Reaction of II with hydrazine gave IISH containing disulfide and thiol groups. Experimental data confirmed the preserved framework structure and the co-existing of disulfide and thiol groups in IISH. Robustness of II and IISH over a wide range of pH (2-10) was confirmed and their mercury removal performances at different pH were evaluated in terms of removal efficiencies (%R), equilibrium uptake capacities (qe) and distribution constant (Kd). The dependence of these parameters on pH is reported. The best values of %R, qe and Kd could be achieved at pH 10 at which surfaces of the adsorbents were negatively charged; 86%R, 429 mg g-1, and 6.04 × 103 mL g-1 (II), and 98%R, 490 mg g-1 and 5.08 × 104 mL g-1 (IISH). At pH 7, influences of the initial concentration of mercury on performances of the adsorbents as well as the adsorption isotherms and kinetics were examined from which the better performance of IISH has been concluded. The characterization of the adsorptions by the Langmuir model and the pseudo-second-order kinetic as well as their excellent consistency with the experimental data are included. At neutral pH, selectivity to the adsorption of mercury and tolerance to common anions were illustrated. The better affinity between mercury and thiol group and therefore its contribution to the better performance of IISH was then ascertained by a computational study.

Crystal structure and photoluminescent properties of a new EuIII-phthalate-acetate coordination polymer.

A new coordination polymer, poly[(acetato)aqua(µ3-phthalato)europium(III)], [Eu(C8H4O4)(CH3O2)(H2O)] n or [EuIII(phth)(OAc)(H2O)] (phth2- = phthalate and OAc- = acetate) was synthesized and characterized, revealing it to be a supra-molecular assembly of one-dimensional [EuIII(phth)(OAc)(H2O)] chains. Each chain is built up of edge-sharing distorted tricapped trigonal-prismatic TPRS-{EuIIIO9} building motifs and assembled in a regular fashion through hydrogen-bonding and aromatic π-π inter-actions. The fully deprotonated phth2- ligand was shown to be an effective sensitizer, promoting the characteristic 5 D 0→7 FJ (J = 1-4) emissions of EuIII even in the presence of the non-sensitizing OAc- group.

Highly Porous Ionic Solids Consisting of AuI3CoIII2 Complex Anions and Aqua Metal Cations.

Treatment of Na3[Au3Co2(d-pen)6] (Na3[1]; d-H2pen = d-penicillamine) with M(OAc)2 (M = NiII, MnII) in water gave ionic crystals of [M(H2O)6]3[1]2 (2M) in which [1]3- anions are hydrogen-bonded with [M(H2O)6]2+ cations to form a 3D porous framework with a porosity of ca. 80%. Soaking crystals of 2Ni in its mother liquor afforded crystals of [Ni(H2O)6]2[{Ni(H2O)4}(1)2] (3Ni) in which [1]3- anions are connected to trans-[Ni(H2O)4]2+ and [Ni(H2O)6]2+ cations through coordination and hydrogen bonds, respectively, to form a 1D porous framework with a porosity ca. 60%. Further soaking crystals led to [{Ni(H2O)4}3(1)2] (4Ni), in which [1]3- anions are connected to cis-[Ni(H2O)4]2+ and trans-[Ni(H2O)4]2+ cations through coordination bonds in a dense framework with a porosity of ca. 30%. A similar two-step crystal-to-crystal transformation mediated by solvent proceeded when crystals of 2Mn were soaked in a mother liquor. However, the transformation of 2Mn generated [{Mn(H2O)4}(H1)] (4'Mn) as the final product, in which [H1]2- anions are connected to cis-[Mn(H2O)4]2+ cations through coordination bonds in a very dense framework with a porosity ca. 5% by way of [Mn(H2O)6]2[{Mn(H2O)4}(1)2] (3Mn), which is isostructural with 3Ni. While all the compounds adsorbed H2O and CO2 depending on the degree of their porosity, unusually large NH3 adsorption capacities were observed for 4Ni and 4'Mn, which have dense frameworks.

Gas Adsorption, Proton Conductivity, and Sensing Potential of a Nanoporous Gadolinium Coordination Framework.

The new nanoporous framework [Gd4(di-nitro-BPDC)4(NO2)3(OH)(H2O)5]·(solvent) (I; di-nitro-BPDC2- = 2,2'-dinitrobiphenyl-4,4'-dicarboxylate) has been designed and synthesized through a simple one-pot reaction. In addition to its exceptional thermal and water stabilities, I exhibited multifunctional properties. A sudden CO2 uptake to a maximum of 4.51 mmol g-1 (195 K and 1 bar) with notable selectivity over O2 and N2 (CO2/O2 = 39 at 195 K and 0.10 bar, CO2/N2 = 46 at 195 K and 0.10 bar) and an isosteric adsorption enthalpy of 20.7(4) kJ mol-1 have been revealed. Depending on the temperature and humidity, I also showed distinguished superprotonic conductivities with a maximum value and activation energy of 6.17 × 10-2 S cm-1 (55 °C, 99 RH%, and 1 V AC voltage) and 0.43 eV, respectively. With respect to the linear dependence of conductivities on both temperature (25-55 °C at 99 RH%) and humidity (55-99 RH% at 25 °C), the potential of I in temperature and humidity sensing was evaluated, disclosing an excellent sensing resolution and exceptional accuracy, precision, and repeatability for the measurements.

Organically pillared layer framework of [Eu(NH2-BDC)(ox)(H3O)].

The non-porous three-dimensional structure of poly[(µ5-2-amino-benzene-1,4-di-carboxyl-ato)(µ6-oxalato)(oxomium)europium(III)], [Eu(C8H5NO4)(C2O4)(H3O)] n or [EuIII(NH2-BDC)(ox)(H3O)] n (NH2-BDC2- = 2-amino-terephthalate and ox2- = oxalate) is constructed from two-dimensional layers of EuIII-carboxyl-ate-oxalate, which are connected by NH2-BDC2- pillars. The basic structural unit of the layer is an edge-sharing dimer of TPRS-{EuIIIO9}, which is assembled through the ox2- moiety. The intra-layer void is partially occupied by TPR-{EuIIIO6} motifs. Weak C-H⋯O and strong, classical intra-molecular N-H⋯O and inter-molecular O-H⋯O hydrogen-bonding inter-actions, as well as weak π-π stacking inter-actions, affix the organic pillars within the framework. The two-dimensional layer can be simplified to a uninodal 4-connected sql/Shubnikov tetra-gonal plane net with point symbol {44.62}.

Crystal structures and Hirshfeld surface analysis of transition-metal complexes of 1,3-azolecarboxylic acids.

The crystal structures of five new transition-metal complexes synthesized using thiazole-2-carboxylic acid (2-Htza), imidazole-2-carboxylic acid (2-H2ima) or 1,3-oxazole-4-carboxylic acid (4-Hoxa), namely diaquabis(thiazole-2-carboxylato-κ2N,O)cobalt(II), [Co(C4H2NO2S)2(H2O)2], 1, diaquabis(thiazole-2-carboxylato-κ2N,O)nickel(II), [Ni(C4H2NO2S)2(H2O)2], 2, diaquabis(thiazole-2-carboxylato-κ2N,O)cadmium(II), [Cd(C4H2NO2S)2(H2O)2], 3, diaquabis(1H-imidazole-2-carboxylato-κ2N3,O)cobalt(II), [Co(C4H2N2O2)2(H2O)2], 4, and diaquabis(1,3-oxazole-4-carboxylato-κ2N,O4)cobalt(II), [Co(C4H2NO3)2(H2O)2], 5, are reported. The influence of the nature of the heteroatom and the position of the carboxyl group in relation to the heteroatom on the self-assembly process are discussed based upon Hirshfeld surface analysis and used to explain the observed differences in the single-crystal structures and the supramolecular frameworks and topologies of complexes 1-5.

Microwave synthesis of ZnO nanoparticles using longan seeds biowaste and their efficiencies in photocatalytic decolorization of organic dyes.

Crude water extract of the ground longan seeds which have been disposed in a large amount annually in Northern Thailand has been used in a simple and rapid microwave synthesis of ZnO nanoparticles. The particles were characterized by the UV-vis spectroscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction, electron diffraction, energy dispersive X-ray spectroscopy, and transmission electron microscopy and revealed to be pure hexagonal phase. Influences of zinc precursor in the extract, microwave power, and irradiation time on particle sizes were studied. The use of 800 W and 30 cycles of the microwave irradiation provided the ZnO particles of 10-100 nm in size with an active surface area, a band gap energy, and a zero-point charge of 35 m2·g-1, 3.42 eV, and pH 7.7, respectively, after the calcination. Photocatalytic efficiencies of the synthesized particles were evaluated through the decolorization of methylene blue, malachite green, methyl orange, and orange II, and proved to be on par with commercially available titanium dioxide (Arroxide®P-25) under the same conditions. The use of the longan seeds biowaste as a sustainable supply of natural reagents for the green synthesis of ZnO nanoparticles which can be employed further for waste water treatment of the local textile dyeing industry is therefore presented. Graphical Abstract.

Crystal structure of (1,3-thia-zole-2-carboxyl-ato-κN)(1,3-thia-zole-2-carb-oxy-lic acid-κN)silver(I).

The linear two-coordinate silver (I) complex [Ag(C4H2NO2S)(C4H3NO2S)] or [Ag(2-Htza)(2-tza)] is reported (2-Htza = 1,3-thia-zole-2-carb-oxy-lic acid). The AgI ion is coordinated by two heterocyclic N atoms from two ligands in a linear configuration, forming a discrete coordination complex. There is an O-H⋯O hydrogen bond between 2-tza- and 2tzaH of adjacent complexes. The hydrogen atom is shared between the two oxygen atoms. This inter-action produces a hydrogen-bonded tape parallel to the [110] direction, which is augmented through inter-molecular C-H⋯O hydrogen-bonding inter-actions between the bound thia-zole groups. There is a further rather long Ag⋯O inter-action [2.8401 (13) Å, compared with a mean of 2.54 (11) Šfor 23 structures in the CSD] that assembles these tapes into columns, between which there are C-H⋯π inter-actions, leading to the formation of a three-dimensional supra-molecular architecture.

Unsaturated Mn(II)-Centered [Mn(BDC)] n Metal-Organic Framework with Strong Water Binding Ability and Its Potential for Dehydration of an Ethanol/Water Mixture.

An unsaturated Mn(II)-centered metal-organic framework was synthesized. The presence of an unsaturated Mn(II) center, together with a guest-responsive structural changing feature, plays a crucial role for strong binding with water, leading to its potential application for water/ethanol separation. In addition, the present framework is thermally stable up to 400 °C, which is beneficial for the regeneration process after adsorption.

Lanthanide Coordination Polymers of Mixed Phthalate/Adipate for Ratiometric Temperature Sensing in the Upper-Intermediate Temperature Range.

Based on the mixed phthalate (phth2-) and adipate (ad2-), [Nd2(ad)(phth)2(H2O)4] (I) and [Ln(ad)0.5(phth)(H2O)2] (Ln = EuIII (II), GdIII (III), TbIII (IV), DyIII (V), ErIII (VI), TmIII (VII), 1EuIII:10TbIII (VIII), 3EuIII:10TbIII (IX), and 5EuIII:10TbIII (X)) were synthesized and characterized. Complexes VIII-X show excellent ratiometric temperature sensing behavior in physiological and higher temperature ranges (303-423 K) rendered by the TbIII-to-EuIII energy transfer process. The efficiency of the process as illustrated through the lifetime measurements depends on both the EuIII:TbIII mole ratio and the temperature. The performance of X in terms of relative sensitivity ( Sr), temperature resolution, and measurement repeatability were determined, revealing the maximum Sr ( Sm) of 1.21%·K-1 at 303 K with reliable temperature resolution and excellent repeatability.

Bis(1,10-phenanthroline-κ(2) N,N')(sulfato-κO)copper(II) ethanol monosolvate.

The crystal structure of the title compound, [Cu(SO4)(C12H8N2)2]·C2H5OH, arises from the assembly of the neutral complex [Cu(SO4)(C12H8N2)2] and an ethanol solvent mol-ecule. The Cu(II) ion is five-coordinate, surrounded by two pairs of N atoms from two independent N,N'-chelating 1,10-phenanthroline ligands, and one O atom of monodentate sulfate ligand, in a distorted trigonal-bipyramidal fashion. Spatial orientation of the ligands and the assembly in the solid state are stabilized by the C-H⋯O hydrogen-bonding inter-actions, established between the O atoms (from the sulfate ligand and the ethanol mol-ecule) and the neighbouring 1,10-phenanthroline mol-ecules. There is also an offset face-to-face π-π stacking between the 1,10-phenanthroline ligands. The ethanol solvent mol-ecule is disordered over two orientations in the ratio 0.663 (10):0.337 (10). The crystal examined was subject to racemic twinning and the refined twin fraction was 0.346 (19).

catena-Poly[[bis-(pyridine-κN)zinc]-µ-5-carb-oxy-benzene-1,3-di-carboxyl-ato-κ(2) O (1):O (3)].

The title one-dimensional coordination polymer, [Zn(C9H4O6)(C5H5N)2] n or [Zn(HBTC)(py)2] n , (I), where BTC is benzene-1,3,5-tricarboxylate and py is pyridine, is a solvent-free polymorph of [Zn(HBTC)(py)2]·2C2H5OH [Yaghi et al. (1997 ▶). Chem. Mater. 9, 1074-1076]. Differences in the spatial arrangements and supra-molecular packing of the [Zn(HBTC)(py)2] n chains in the two structures are described. The chain in (I) extends parallel to [100] and is severely puckered, with a Zn⋯Zn distance of 8.3599 (3) Šand a Zn⋯Zn⋯Zn angle of 107.516 (3)°, as a result of hydrogen-bonding inter-actions of the types O-H⋯O and C-H⋯O. There is no evidence for π-π inter-actions in (I). The differences between the solvent-free and solvent-containing structures can be accounted for by the absence of the ethanol solvent mol-ecule and the use of the converging pair of O atoms in the bis-monodentate bridging HBTC(2-) ligand in (I).

µ3-Methoxido-κ(3) O:O:O-tris-(µ-l-p-tyrosinato-κ(3) N,O:O)tris-(l-p-tyrosinato-κ(2) N,O)trinickel(II,III) methanol tetra-solvate.

A trinuclear nickel complex, [Ni3(C9H10NO3)6(CH3O)]·4CH4O, was synthesized and characterized as a neutral cluster containing the incomplete cubane {Ni3(µ1-O)(µ2-O)2(µ3-O)} core of 2M3-1 topology. The three nickel cations show similar octa-hedral coordination, {Ni(µ1-O)(µ2-O)2(µ3-O)(µ1-N)2}; the positive charge is balanced by six tyrosinate ligands and one methoxide ion. The mean oxidation state of each Ni(II) ion is therefore +2.33. The common coordination modes, chelating (via the amino N and the carboxyl-ate O atoms) and bridging (via the carboxyl-ate O atom), are exhibited by the tyrosinates. Three inter-ligand (intra-cluster) N-H⋯O hydrogen-bonding inter-actions stabilize the incomplete cubane-type moiety. Additional N-H⋯O, O-H⋯O and C-H⋯O inter-actions are formed between clusters, and between the clusters and methanol mol-ecules to regulate the spatial orientation of the tyrosinate and the assembly of the clusters in the crystal. The approximate equilateral triangular arrangement of the three nickel cations in the incomplete cubane-type moiety suggests the possible magnetic frustration, and the proximity of these metal cations indicates weak metallic bonds. The structure contains approximately 39% solvent-accessible volume between the clusters. This is filled with 17 mol-ecules of disordered methanol and was modelled with SQUEEZE [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the reported unit-cell characteristics do not take these mol-ecules into account. The H atoms of the solvent mol-ecules have not been included in the crystal data.

(1R,3R,4R,6S)-4-(7-Meth-oxy-2-oxo-2H-chromen-6-yl)-1-methyl-3,6-dioxa-bicyclo-[3.1.0]hexan-2-yl acetate.

In the title compound, C17H16O7, which was isolated from the leaves of Micromelum integerrimum, the furan ring adopts an envelope conformation with the O atom as the flap. An intra-molecular C-H⋯O hydrogen bond occurs. The carbonyl O atom is disordered in a 0.57 (8):0.43 (8) ratio. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds into a C(10) chain along [010].