Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Angew Chem Int Ed Engl ; 61(6): e202115854, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34877789

RESUMO

Under topological guidance, the self-assembly process based on a tetratopic porphyrin synthon results in a hydrogen-bonded organic framework (HOF) with the predicted square layers topology (sql) but unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO2 to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO2 reduction.

2.
Chemistry ; 27(35): 9180-9192, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-33871132

RESUMO

Hydroxyisophthalic acids are valuable polytopic ligands for the design of functional materials based on coordination polymers due to the variety of charges and coordination modes they possess. Herein, we describe the synthesis, thermal stability, nonlinear optical (NLO) and spectroscopic properties of five novel coordination compounds, [K2 L(H2 O)2 ], [MgL(H2 O)2 ] ⋅ 3H2 O, [CaL(H2 O)3 ], [SrL(H2 O)3 ] ⋅ H2 O, [BaL(H2 O)(H2 O)5 ], and one salt, (NH4 )2 L ⋅ 2H2 O, with 4,5,6-trihydroxyisophthalic acid (H2 L), which has not been tested in assembling crystalline coordination networks before. The peculiarities of the structural organization of the compounds were analyzed and compared with those for other hydroxyisophthalates. The coordination properties of hydroxyisophthalic acids were studied from the topological point of view, and a comparative topological analysis of coordination and H-bonded networks was performed. Structural correlations revealed in this study could be useful for the design of hydroxyisophthalate-based coordination networks, including porous metal-organic frameworks, proton conductors, and NLO materials.

3.
Chem Commun (Camb) ; 56(67): 9616-9619, 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32701103

RESUMO

We present the results of a comprehensive geometrical and topological analysis of 3D coordination networks in 33 790 coordination polymers. We have found relations between topological descriptors and free space of the networks, and have revealed topological types that promote high porosity of metal-organic frameworks.

4.
Dalton Trans ; 49(21): 7084-7092, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32406437

RESUMO

In crystal structures of two chain coordination polymers [M(tcnopr3OH)2(H2O)2] (M = NiII and CoII; tcnopr3OH- = [(NC)2CC(O(CH2)3OH)C(CN)2]-) based on a N,O or N,N'-bridge polynitrile ligand, the parallel chains are connected via, respectively, C[triple bond, length as m-dash]NH-O and O-HO hydrogen bonds between uncoordinated functional groups of the ligand and coordinated water molecules. Upon heating, both solids undergo dehydration accompanied by degradation of their single crystals. Powder X-ray diffraction showed that non-isostructural triclinic single crystals transformed to isostructural monoclinic compounds. The solid-state reaction yielded 3D coordination polymers [M(tcnopr3OH)2] (M = NiII and CoII) based on a N,N',O-connected tcnopr3OH-. Although previously tens of complexes based on tcnopr3OH and similar anions were synthesized and X-ray characterized, none of these contain a tridentate polynitrile ligand. Thus, this study provides evidence that solid-state reactions allow obtaining novel coordination modes of polynitrile ligands. The possible pathways for the transformation of H-bonded networks to 3D coordination polymers are discussed on the basis of the topological approach. Applicability of the topological approach to predict possible networks of solid-state reaction products based on the crystal structures of initial compounds is demonstrated.

5.
J Am Chem Soc ; 142(15): 7218-7224, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32212652

RESUMO

Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal honeycomb motifs which are extended into undulated two-dimensional (2D) layers and finally generate three polycatenated HOFs with record complexity. This kind of undulation is absent in the 2D layers built from a very similar but nonplanar ligand, indicating that a slight torsion of ligand produces overwhelming structural change. This change delivers materials with unique stepwise adsorption behaviors under a certain pressure originating from the movement between mutually interwoven hexagonal networks. Meanwhile, high chemical stability, phase transformation, and preferential adsorption of aromatic compounds were observed in these HOFs. The results presented in this work would help us to understand the self-assembly behaviors of HOFs and shed light on the rational design of HOF materials for practical applications.

6.
Chem Sci ; 10(37): 8558-8565, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31762972

RESUMO

We report three electrically conductive metal-organic frameworks (MOFs) based on a tetrathiafulvalene linker and La3+. Depending on the solvent ratios and temperatures used in their solvothermal synthesis, these MOFs crystallize with different topologies containing distinct π-π stacking sequences of the ligand. Notably, their transport properties correlate rationally with the stacking motifs: longer S···S contact distances between adjacent ligands coincide with lower electrical conductivities and higher activation energies. Diffuse reflectance spectroscopic measurements reveal ligand-based intervalence charge transfer bands in each phase, implicating charge delocalization among mixed-valent tetrathiafulvalene units as the dominant mode of transport. Overall, these frameworks demonstrate how tuning the intermolecular interactions in MOFs serves as a route towards controlling their physical properties.

7.
J Am Chem Soc ; 141(27): 10915-10923, 2019 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-31246447

RESUMO

Covalently linked single-crystalline porous organic materials are highly desired for structure-property analysis; however, periodically polymerizing organic entities into high dimensional networks is challenging. Here, we report a series of topologically divergent single-crystalline hydrogen-bonded cross-linked organic frameworks (HCOFs) with visible guest-induced elastic expansions, which mutually integrate high structural order and high flexibility into one framework. These HCOFs are synthesized by photo-cross-linking molecular crystals with alkyldithiols of different chain lengths. Their detailed structural information was revealed by single-crystal X-ray analysis and experimental investigations of HCOFs and their corresponding single-crystalline analogues. Upon guest adsorption, HCOF-2 crystals composed of a 3D self-entangled polymer network undergo anisotropic expansion to more than twice their original size, while the 2D-bilayer HCOF-3 crystals exhibit visible, layered sorption bands and form delaminated sheets along the plane of its 2D layers. The dynamic expansion of HCOF networks creates guest-induced porosity with over 473% greater volume than their permanent voids, as calculated from their record-breaking aqueous iodine adsorption capacities. Temperature-gated DMSO sorption investigations illustrated that the flexible nature of cross-linkers in HCOFs provides positive entropy from the coexistence of multiple conformations to allow for elastic expansion and contraction of the frameworks.

8.
Dalton Trans ; 48(16): 5450-5458, 2019 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-30957800

RESUMO

Six metal-organic frameworks with the combination of a novel tripodal ligand tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide (tipo) and different polycarboxylates, namely [Zn2(bpdc)2(tipo)(H2O)]·5H2O (1), [Cd(tipo)2][Cd2(bdc)3]·4H2O (2), [Cd2(ndc)2(tipo)2]·3H2O (3), [Cd2(bpedc)2(tipo)2]·15H2O (4), [Cd2(hfdc)2(tipo)2]·10H2O (5) and [Ni2(tipo)2(bpedc)(H2O)4]·2NO3·2DMF (6), were synthesized and structurally characterized. Compound 1 featured a 2D → 3D parallel polycatenation of a 3,3,4-connected net with an unusual 4 degrees of catenation and an index of separation of 2. Compound 2 showed an unprecedented polycatenation of charged networks 2D kgd and 3D pcu constructed by different organic ligands. Compound 3 exhibited a combination of a 2D → 3D parallel polycatenation of the sql net and polythreading. Compound 4 featured a 4-fold interpenetration of a 3,5-connected 3,5T1 net. Compound 5 displayed an unusual 2-fold interpenetration of the sdd net. Compound 6 presented a 2-fold interpenetration of the 3,4-connected bey net with a cationic framework. The luminescence properties of 1-5 in the solid state were investigated. Also, compound 6 showed a tendency for rapid selective dye capture and highly efficient Cr2O72- removal from aqueous solution.

9.
Nat Commun ; 9(1): 1745, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29717138

RESUMO

As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr6O4(OH)4(bptc)3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr6O4(OH)8(H2O)4(abtc)2, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.

10.
Cryst Growth Des ; 18(3): 1738-1747, 2018 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-29541002

RESUMO

We consider two metal-organic frameworks as identical if they share the same bond network respecting the atom types. An algorithm is presented that decides whether two metal-organic frameworks are the same. It is based on distinguishing structures by comparing a set of descriptors that is obtained from the bond network. We demonstrate our algorithm by analyzing the CoRe MOF database of DFT optimized structures with DDEC partial atomic charges using the program package ToposPro.

11.
Chem Rev ; 115(22): 12286-319, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26505277

RESUMO

This review focuses on topological features of three-periodic (framework) p, d, and f metal cyano complexes or cyanometallates, i.e. coordination compounds, where CN(-) ligands play the main structure-forming role. In addition, molecular, one-periodic (chain), and two-periodic (layer) cyanometallates are considered as possible building blocks of the three-periodic cyanometallates. All cyanometallates are treated as systems of nodes (mononuclear, polynuclear, or transitional metal cluster complexes) joined together via CN-containing spacers. The most typical nodes and spacers as well as methods of their connection are described and systematized. Particular attention is paid to the overall structural motifs in the three-periodic cyanometallates, especially to the relations between the local coordination (coordination figure) of structural units and the entire framework topology. The chemical factors are discussed that influence the cyanometallate topological properties due to modification of nodes, spacers, or coordination figures.


Assuntos
Nitrilas/química , Compostos Organometálicos/química , Modelos Moleculares
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...