@article{luo_lin_li_smirnova_maggard_2014, title={Copper-Organic/Octamolybdates: Structures, Bandgap Sizes, and Photocatalytic Activities}, volume={53}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/IC402910A}, DOI={10.1021/ic402910a}, abstractNote={The structures, optical bandgap sizes, and photocatalytic activities are described for three copper-octamolybdate hybrid solids prepared using hydrothermal methods, [Cu(pda)]4[β-Mo8O26] (I; pda = pyridazine), [Cu(en)2]2[γ-Mo8O26] (II; en = ethylenediamine), and [Cu(o-phen)2]2[α-Mo8O26] (III; o-phen = o-phenanthroline). The structure of I consists of a [Cu(pda)]4(4+) tetramer that bridges to neighboring [β-Mo8O26](4-) octamolybdate clusters to form two-dimensional layers that stack along the a axis. The previously reported structures of II and III are constructed from [Cu2(en)4Mo8O26] and [Cu2(o-phen)4Mo8O26] clusters. The optical bandgap sizes were measured by UV-vis diffuse reflectance techniques to be ∼1.8 eV for I, ∼3.1 eV for II, and ∼3.0 eV for III. Electronic structure calculations show that the smaller bandgap size of I originates primarily from an electronic transition between the valence and conduction band edges comprised of filled 3d(10) orbitals on Cu(I) and empty 4d(0) orbitals on Mo(VI). Both II and III contain Cu(II) and exhibit larger bandgap sizes. Accordingly, aqueous suspensions of I exhibit visible-light photocatalytic activity for the production of oxygen at a rate of ∼90 μmol O2 g(-1) h(-1) (10 mg samples; radiant power density of ∼1 W/cm(2)) and a turnover frequency per calculated surface [Mo8O26](4-) cluster of ∼36 h(-1). Under combined ultraviolet and visible-light irradiation, I also exhibits photocatalytic activity for hydrogen production in 20% aqueous methanol of ∼316 μmol H2 g(-1) h(-1). By contrast, II decomposed during the photocatalysis measurements. The molecular [Cu2(o-phen)4(α-Mo8O26)] clusters of III dissolve into the aqueous methanol solution under ultraviolet irradiation and exhibit homogeneous photocatalytic rates for hydrogen production of up to ∼8670 μmol H2·g(-1) h(-1) and a turnover frequency of 17 h(-1). The clusters of III can be precipitated out by evaporation and redispersed into solution with no apparent decrease in photocatalytic activity. During the photocatalysis measurements, the dissolution of the clusters in III is found to occur with the reduction of Cu(II) to Cu(I), followed by subsequent detachment from the octamolybdate cluster. The lower turnover frequency, but higher photocatalytic rate, of III arises from the net contribution of all dissolved [Cu2(o-phen)4(α-Mo8O26)] clusters, compared to only the surface clusters for the heterogeneous photocatalysis of I.}, number={7}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Luo, Lan and Lin, Haisheng and Li, Le and Smirnova, Tatyana I. and Maggard, Paul A.}, year={2014}, month={Mar}, pages={3464–3470} }
 @article{zou_lin_maggard_deiters_2011, title={Efficacy of C-N Coupling Reactions with a New Multinuclear Copper Complex Catalyst and Its Dissociation into Mononuclear Species}, volume={2011}, ISSN={["1099-0690"]}, DOI={10.1002/ejoc.201100399}, abstractNote={Abstract}, number={22}, journal={EUROPEAN JOURNAL OF ORGANIC CHEMISTRY}, author={Zou, Yan and Lin, Haisheng and Maggard, Paul A. and Deiters, Alexander}, year={2011}, month={Aug}, pages={4154–4159} }
 @article{lin_maggard_2011, title={Investigation of Trimetallic Ligand-Pillared Oxyfluorides: Ag2Cu(pzc)2MO x F6−x (M = Mo, Nb, and W)}, volume={41}, ISSN={["1572-8854"]}, DOI={10.1007/s10870-011-0139-y}, number={10}, journal={Journal of Chemical Crystallography}, author={Lin, H and Maggard, P.A.}, year={2011}, pages={1552–1559} }
 @article{lin_maggard_2010, title={Microporosity, Optical Bandgap Sizes, and Photocatalytic Activity of M(I)-Nb(V) (M = Cu, Ag) Oxyfluoride Hybrids}, volume={10}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/cg9013625}, DOI={10.1021/cg9013625}, abstractNote={Using hydrothermal methods, a new series of five M(I)−Nb(V) oxyfluoride hybrid solids was prepared having the compositions [Cu(pyz)]2NbOF5 (1, pyz = pyrazine), Ag(pyz)NbOF4 (2), M(bpy)NbOF4·2H2O (3, M = Cu; 4, M = Ag; bpy = 4,4′-bipyridine), and [Cu(dpe)]2NbOF5·8H2O (5, dpe = 1,2-bis(4-pyridyl)-ethene). Each of the hybrid solids consists of layered structures with bridging ligands that coordinate via the Ag+ or Cu+ (i.e., M+) sites in each layer. The structure of 1 is comprised of [Cu2(pyz)22+]n double chains that are cross-linked into double layers by coordination to partially O/F-disordered [NbOF5]2− octahedra. Hybrids 2−4 contain pyz- and bpy-pillared [MNbOF4] layers, with the longer bpy ligand affording two interlayer water molecules per M+ site. These [MNbOF4] layers consist of ordered polar [NbOF4]− chains that are bridged via the M+ sites and that orient in alternating directions. The longest ligand in 5, dpe, results in a 3-fold interpenetrating pillared network consisting of [Cu(dpe)+]n chains br...}, number={3}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Lin, Haisheng and Maggard, Paul A.}, year={2010}, month={Mar}, pages={1323–1331} }
 @article{lin_wu_maggard_2009, title={Ligand-Based Modification of the Structures and Optical Properties of New Silver(I)-Rhenate(VII) Oxide/Organic Hybrid Solids}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic901749r}, abstractNote={A new series of silver(I)-rhenate(VII) hybrids was systematically prepared under hydrothermal conditions from eight different N-donor organic ligands (isonicotinate = inca, pyrazine-2-carboxylate = pzc, 1,2,4-triazole = tro, pyridazine = pda, 4,4'-bipyridine = bpy, 1,2-bis(4-pyridyl)-ethane = dpa, 2,3-bis(2-pyridyl)pyrazine = bpp, and tetra-2-pyridinylpyrazine = tpp), and their resulting structures and optical properties were investigated. The reactions targeted a 1:1 molar ratio of Ag/Re, and new hybrid solids were prepared with the compositions Ag(bpp)ReO(4) (1), Ag(tpp)ReO(4) x H(2)O (2), Ag(Hinca)(2)ReO(4) x H(2)O (3), Ag(tro)ReO(4) (4), Ag(pda)ReO(4) x 1/2 H(2)O (5), Ag(Hpzc)ReO(4) (6), Ag(2)(Hpzc)(pzc)(H(2)O)ReO(4) (7), Ag(bpy)ReO(4) (8), and Ag(dpa)(2)ReO(4) (9). Hybrid solids 1, 2, and 3 each exhibit low-dimensional structures, consisting of [Ag(2)(bpp)(4)](2+) and [Ag(2)(Hinca)(4)](2+) dimers in 1 and 3, respectively, and [Ag(tpp)](n)(n+) chains in 2. Hybrid solids 4 and 5 contain a [Ag(tro)](+) chain and a [Ag(3)(pda)(3)](3+) cyclic trimer, respectively, that are both ReO(4)-bridged into layered structures. Both 6 and 8 consist of ligand-pillared "AgReO(4)" layers, while 7 is a Re-deficient analogue of 6 that contains ligand-pillared [Ag(2)(H(2)O)ReO(4)](+) layers where H(2)O replaces the missing ReO(4)(-) anion. The hybrid networks of 8 and 9 are interpenetrating, owing to the length of the bpy and dpa ligands, and consist of bpy-pillared "AgReO(4)" layers and ReO(4)-filled [Ag(dpa)(2)](+) diamond-type networks that are 2-fold and 6-fold interpenetrating, respectively. Their optical properties and thermal stabilities were investigated using UV-vis transmittance, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The measured properties were analyzed with respect to the varying structural modifications. The Ag-ReO(4) network dimensionalities, Ag coordination environments, and the ligand lengths and geometries are found to play important roles in the absorption coefficients, bandgap sizes, and whether the structure collapses softly to give condensed AgReO(4), respectively.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Lin, Haisheng and Wu, Xiaomeng and Maggard, Paul A.}, year={2009}, month={Dec}, pages={11265–11276} }
 @article{lin_maggard_2009, title={Ligand-Mediated Interconversion of Multiply-Interpenetrating Frameworks in Cu-I/Re-VII-Oxide Hybrids}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic900735n}, abstractNote={Two new copper(I)-rhenate(VII) hybrid solids, Cu(bpy)ReO(4) (I) and Cu(bpy)(2)ReO(4).0.5H(2)O (II) (bpy = 4,4'-bipyridine), with 2-fold and 4-fold interpenetrating networks, respectively, were prepared from hydrothermal reactions, and their structures characterized by single-crystal X-ray diffraction [I, Pbca (No. 61), Z = 8, a = 10.8513(3) A, b = 12.9419(4) A, c = 15.6976(5) A; II, P1 (No. 2), Z = 2, a = 11.8190(4) A, b = 12.6741(4) A, c = 13.7585(5) A, alpha = 85.8653(13) degrees, beta = 81.6197(13) degrees, gamma = 84.0945(11) degrees]. The structure of I contains 6(3) nets of neutral CuReO(4) layers that are pillared via bpy ligands on the Cu sites {CuO(3)N(2)} to yield a 2-fold interpenetrating pillared-layered network. Conversely, the structure of II consists of a 4-fold interpenetrating diamond-type network with tetrahedral {CuN(4)} coordination nodes that are bridged by bpy ligands, with both H(2)O and ReO(4)(-) within the pores. A surprising reversible structural interconversion between these two interpenetrating structures is possible via the insertion and removal of a single bpy ligand and (1/2)H(2)O per copper atom. The structural interconversion is accompanied by a change in color from yellow to red for I and II, respectively. Measured UV-vis diffuse reflectance spectra exhibit a significant red-shift in the absorption edge of approximately 0.3 eV, with the optical bandgap size decreasing from approximately 2.5 eV to approximately 2.2 eV for I and II, respectively. X-ray photoelectron spectra and electronic structure calculations indicate that the valence band derived from the Cu 3d and N 2p orbitals in II are pushed higher in energy compared to those in I because of the coordination of the additional bpy ligand. There is a much smaller change in the energy of the conduction band that is derived from the Re 5d orbitals. These results demonstrate that the ligand-mediated structural transformations of (d(0)/d(10))-hybrid solids represent a new and convenient low-temperature approach to modulate their optical bandgap sizes toward the visible wavelengths for use with solar energy.}, number={18}, journal={INORGANIC CHEMISTRY}, author={Lin, Haisheng and Maggard, Paul A.}, year={2009}, month={Sep}, pages={8940–8946} }
 @article{lin_maggard_2008, title={Synthesis and structures of a new series of silver-vanadate hybrid solids and their optical and photocatalytic properties}, volume={47}, ISSN={["1520-510X"]}, DOI={10.1021/ic8004129}, abstractNote={Three new silver-vanadate hybrid solids, [Ag(bpy)]4V4O12 x 2 H2O (I), [Ag(dpa)]4V4O12 x 4 H2O (II), and Ag4(pzc)2V2O6 (III) (bpy = 4,4'-bipyridine, dpa = 1,2-bis(4-pyridyl)-ethane, pzc = pyrazinecarboxylate), were synthesized by hydrothermal methods and characterized using single crystal X-ray diffraction (I, P2(1)/c, Z = 4, a = 11.375(2) A, b = 14.281(4) A, c = 13.598(3) A, beta = 91.46(1) degrees; II, P2(1)/c, Z = 8, a = 13.5748(3) A, b = 15.3372(4) A, c = 14.1854(3) A, beta = 114.1410(9) degrees; III, P1, Z = 2, a = 3.580(1) A, b = 11.839(4) A, c = 19.321(7) A, alpha = 89.110(7) degrees, beta = 87.719(9) degrees, gamma = 86.243(8) degrees), thermogravimetric analysis, and UV-vis diffuse reflectance. The structures of I and II are constructed from neutral {Ag4V4O12}n layers of clusters that are pillared via the coordination of organic ligands (bpy for I and dpa for II) to the Ag sites in each layer. Conversely, the structure of III is composed of a three-dimensional {Ag2(pzc)(+)}n coordination network with channels containing {VO3(-)}n chains. The lattice water molecules can be removed upon heating to > or = 180 degrees C for I (reversibly) and to > or = 120 degrees C for II (irreversibly). All three decompose with the removal of organic ligands at higher temperatures of > 200-300 degrees C. Their optical bandgap sizes were measured to be 2.77 eV for I, 2.95 eV for II, and 2.45 eV for III, which decrease most notably as a result of the band widening for the more extended vanadate structure in III. All three hybrid solids are photocatalytically active for the decomposition of methylene blue under UV light (lambda < 400 nm; 1.01, 0.64, and 2.65 mg L(-1) h(-1) for I, II, and III, respectively), while only III exhibits a high activity under visible-light irradiation (lambda > 400 nm; 1.20 mg L(-1) h(-1) ). These new hybrid solids are among the first reported to exhibit high photocatalytic activities under either ultraviolet or visible-light irradiation and have also been analyzed with respect to the effect of the different organic ligands on their atomic- and electronic-structures.}, number={18}, journal={INORGANIC CHEMISTRY}, author={Lin, Haisheng and Maggard, Paul A.}, year={2008}, month={Sep}, pages={8044–8052} }
 @article{lin_maggard_2007, title={Copper(I)-rhenate hybrids: Syntheses, structures, and optical properties}, volume={46}, ISSN={["0020-1669"]}, DOI={10.1021/ic061767g}, abstractNote={The new copper(I) rhenates, CuReO4(pyz) (I) and Cu3ReO4(q6c)2 (II) (pyz = pyrazine; q6c = quinoline-6-carboxylate), were synthesized by hydrothermal methods at 140-150 degrees C, and their structures determined via single-crystal X-ray diffraction (I, P21/n, No. 14, Z = 4, a = 7.972(1) A, b = 11.928(2) A, c = 8.430(1) A, beta = 102.161(2) degrees ; II, P21, No. 4, Z = 2, a = 8.253(2) A, b = 6.841(2) A, c = 18.256(6) A, beta = 101.37(2) degrees ) and characterized by thermogravimetric analyses and UV-vis diffuse reflectance. The structure of I contains 'CuReO4' layers that are pillared through bridging pyrazine ligands via the Cu sites, while the structure of II is polar and contains chains of 'Cu2ReO4' that are condensed into layers by coordination to linear 'Cu(q6c)2' bridges between the chains. In contrast to air-sensitive CuReO4, both hybrid analogues are stable in air owing to a stabilization of the Cu1+ oxidation state by N-donating ligands, but decompose upon heating with the removal of the organic ligands, which for I yields crystalline CuReO4. UV-vis diffuse reflectance measurements and electronic structure calculations on all three copper perrhenates, I, II, and CuReO4, show that each exhibits an optical band gap of approximately 2.1-2.2 eV, with conduction and valence band levels that are primarily derived from the Re d0 and Cu d10 orbitals, respectively, and mixed with O p-orbital contributions. In contrast to the silver rhenates, which have relatively lower energy Ag d10 orbitals, the inclusion of the organic ligands into the structures has only a very minor effect ( approximately 0.1 eV) on the band gap size. The optical absorptions, in combination with the air-stable open-framework layered structures, illustrate that heterometallic Cu1+/Re7+ oxides can be promising candidates for investigating in visible-light photocatalytic reactions.}, number={4}, journal={INORGANIC CHEMISTRY}, author={Lin, Haisheng and Maggard, Paul A.}, year={2007}, month={Feb}, pages={1283–1290} }