Cheng Wang

Catalytically competent Ir, Re, and Ru complexes H(2)L(1)-H(2)L(6) with dicarboxylic acid functionalities were incorporated into a highly stable and porous Zr(6)O(4)(OH)(4)(bpdc)(6) (UiO-67, bpdc = para-biphenyldicarboxylic acid) framework using a mix-and-match synthetic strategy. The matching ligand lengths between bpdc and L(1)-L(6) ligands allowed the construction of highly crystalline UiO-67 frameworks (metal-organic frameworks (MOFs) 1-6) that were doped with L(1)-L(6) ligands. MOFs 1-6 were isostructural to the parent UiO-67 framework as shown by powder X-ray diffraction (PXRD) and exhibited high surface areas ranging from 1092 to 1497 m(2)/g. MOFs 1-6 were stable in air up to 400 °C and active catalysts in a range of reactions that are relevant to solar energy utilization. MOFs 1-3 containing [Cp*Ir(III)(dcppy)Cl] (H(2)L(1)), [Cp*Ir(III)(dcbpy)Cl]Cl (H(2)L(2)), and [Ir(III)(dcppy)(2)(H(2)O)(2)]OTf (H(2)L(3)) (where Cp* is pentamethylcyclopentadienyl, dcppy is 2-phenylpyridine-5,4'-dicarboxylic acid, and dcbpy is 2,2'-bipyridine-5,5'-dicarboxylic acid) were effective water oxidation catalysts (WOCs), with turnover frequencies (TOFs) of up to 4.8 h(-1). The [Re(I)(CO)(3)(dcbpy)Cl] (H(2)L(4)) derivatized MOF 4 served as an active catalyst for photocatalytic CO(2) reduction with a total turnover number (TON) of 10.9, three times higher than that of the homogeneous complex H(2)L(4). MOFs 5 and 6 contained phosphorescent [Ir(III)(ppy)(2)(dcbpy)]Cl (H(2)L(5)) and [Ru(II)(bpy)(2)(dcbpy)]Cl(2) (H(2)L(6)) (where ppy is 2-phenylpyridine and bpy is 2,2'-bipyridine) and were used in three photocatalytic organic transformations (aza-Henry reaction, aerobic amine coupling, and aerobic oxidation of thioanisole) with very high activities. The inactivity of the parent UiO-67 framework and the reaction supernatants in catalytic water oxidation, CO(2) reduction, and organic transformations indicate both the molecular origin and heterogeneous nature of these catalytic processes. The stability of the doped UiO-67 catalysts under catalytic conditions was also demonstrated by comparing PXRD patterns before and after catalysis. This work illustrates the potential of combining molecular catalysts and MOF structures in developing highly active heterogeneous catalysts for solar energy utilization.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRational Synthesis of Noncentrosymmetric Metal–Organic Frameworks for Second-Order Nonlinear OpticsCheng Wang, Teng Zhang, and Wenbin Lin*View Author Information Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, United States*Phone: 919-962-6320. Fax: 919-962-2388. E-mail: [email protected]Cite this: Chem. Rev. 2012, 112, 2, 1084–1104Publication Date (Web):November 9, 2011Publication History Received7 July 2011Published online9 November 2011Published inissue 8 February 2012https://pubs.acs.org/doi/10.1021/cr200252nhttps://doi.org/10.1021/cr200252nreview-articleACS PublicationsCopyright © 2011 American Chemical SocietyRequest reuse permissionsArticle Views13889Altmetric-Citations911LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Ligands,Metal organic frameworks,Nonlinear optics,Space group,Urea Get e-Alerts

Metal-organic frameworks (MOFs), also known as coordination polymers, represent an interesting class of crystalline molecular materials that are synthesized by combining metal-connecting points and bridging ligands. The modular nature of and mild conditions for MOF synthesis have permitted the rational structural design of numerous MOFs and the incorporation of various functionalities via constituent building blocks. The resulting designer MOFs have shown promise for applications in a number of areas, including gas storage/separation, nonlinear optics/ferroelectricity, catalysis, energy conversion/storage, chemical sensing, biomedical imaging, and drug delivery. The structure-property relationships of MOFs can also be readily established by taking advantage of the knowledge of their detailed atomic structures, which enables fine-tuning of their functionalities for desired applications. Through the combination of molecular synthesis and crystal engineering, MOFs thus present an unprecedented opportunity for the rational and precise design of functional materials.

Metal–organic frameworks (MOFs), a new class of crystalline molecular solids built from linking organic ligands with metal or metal-cluster connecting points, have recently emerged as a versatile platform for developing single-site solid catalysts. MOFs have been used to drive a range of reactions, including Lewis acid/base catalyzed reactions, redox reactions, asymmetric reactions, and photocatalysis. MOF catalysts are easily separated from the reaction mixtures for reuse, and yet their molecular nature introduces unprecedented chemical diversity and tunability to drive a large scope of catalytic reactions. This Perspective aims to summarize recent progress on light harvesting and photocatalysis with MOFs. The charge-separated excited states of the chromophoric building blocks created upon photon excitation can migrate over long distances to be harvested as redox equivalents at the MOF/liquid interfaces via electron transfer reactions or can directly activate the substrates that have diffused into the MOF channels for photocatalytic reactions. MOF-catalyzed and photodriven proton reduction, CO2 reduction, and organic transformations will be discussed in this Perspective.

Pt nanoparticles of 2-3 nm and 5-6 nm in diameter were loaded into stable, porous, and phosphorescent metal-organic frameworks (MOFs 1 and 2) built from [Ir(ppy)(2)(bpy)](+)-derived dicarboxylate ligands (L(1) and L(2)) and Zr(6)(μ(3)-O)(4)(μ(3)-OH)(4)(carboxylate)(12) secondary building units, via MOF-mediated photoreduction of K(2)PtCl(4). The resulting Pt@MOF assemblies serve as effective photocatalysts for hydrogen evolution by synergistic photoexcitation of the MOF frameworks and electron injection into the Pt nanoparticles. Pt@2 gave a turnover number of 7000, approximately five times the value afforded by the homogeneous control, and could be readily recycled and reused.