Browsing by Author "Wojtas, Lukasz"
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Item Copper(II) Complexes with Tridentate Bis(pyrazolylmethyl)pyridine Ligands: Synthesis, X-ray Crystal Structures and ϵ-Caprolactone Polymerization(Wiley-Blackwell, 2017-10) Rueda‐Espinosa, Juan; Torres, Juan F.; Gauthier, Carmen Valdez; Wojtas, Lukasz; Verma, Gaurav; Macías, Mario A.; Hurtado, JohnAbstract: Reactions of Cu(ClO4)2⋅6H2O with 2,6‐bis(3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (dmpz‐py) (1), 2,6‐bis(4‐iodo‐3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (I‐dmpz‐py) (2) and 2,6‐bis(4‐nitro‐3,5‐dimethylpirazol‐1‐ylmethyl)pyridine (NO2‐dmpz‐py) (3) yield the corresponding metal complexes: [Cu(dmpz‐py)(H2O)(ClO4)]ClO4 (4), [Cu(I‐dmpz‐py)(H2O)](ClO4)2 (5) and [Cu(NO2‐dmpz‐py)(H2O)(ClO4)2] (6). The complexes were isolated in high yields as stable solids at room temperature and characterized by melting point, electrical conductivity, and infrared and ultraviolet/visible spectroscopy. In addition, the crystal structures of the new complexes were determined by single‐crystal X‐ray diffraction and showed square‐base pyramidal (4), distorted square‐planar (5) and octahedral (6) geometries. All three complexes were active in the ring opening polymerization of ϵ‐caprolactone under solvent‐free conditions, producing polycaprolactones of narrow polydispersity and high crystallinity. The results obtained show an important increase in polymerization speed compared with analogous azole‐derived copper (II) complexes. [ABSTRACT FROM AUTHOR]Item Poly(methyl methacrylate) composites of copper-4,4′-trimethylenedipyridine(Royal Society of Chemistry, 2012) Liu, Shisi; Ananthoji, Ramakanth; Han, Sungyub; Knudsen, Bernard; Li, Xiao; Wojtas, Lukasz; Massing, Justin; Gauthier, Carmen Valdez; Harmon, Julie P.We prepared a series of poly(methyl methacrylate) (PMMA) composites with a novel one dimensional coordination polymer copper-4,4′-trimethylenedipyridine (CU-TMDP). The CU-TMDP was sonicated in a methyl methacrylate monomer and polymerized in situ. Thermal, mechanical and optical properties of CU-TMDP–PMMA composites were probed via optical microscopy, Raman spectroscopy, differential scanning calorimetry (DSC), microhardness, and dynamic mechanical analysis (DMA). The CU-TMDP was characterized by X-ray crystallography. The functionality of the CU-TMDP interacted with the polymer matrix such that mechanical properties are tuned by varying CU-TMDP loadings. The data point to the fact that interactions are primarily due to London dispersion forces or dipole–dipole interactions. This initial study forms the basis for future applications requiring tailored mechanical properties.Item Poly(methyl methacrylate) composites of copper-4,4′-trimethylenedipyridine(New Journal of Chemistry, 2012-07) Liu, Shisi; Ananthoji, Ramakanth; Han, Sungyub; Knudsen, Bernard; Li, Xiao; Wojtas, Lukasz; Massing, Justin; Gauthier, Carmen Valdez; Harmon, Julie P.A series of poly(methyl methacrylate) (PMMA) composites were prepared with a novel one dimensional coordination polymer copper-4,4′-trimethylenedipyridine (CU-TMDP). The CU-TMDP was sonicated in a methyl methacrylate monomer and polymerized in situ. Thermal, mechanical and optical properties of CU-TMDP–PMMA composites were probed via optical microscopy, Raman spectroscopy, differential scanning calorimetry (DSC), microhardness, and dynamic mechanical analysis (DMA). The CU-TMDP was characterized by X-ray crystallography. The functionality of the CU-TMDP interacted with the polymer matrix such that mechanical properties are tuned by varying CU-TMDP loadings. The data point to the fact that interactions are primarily due to London dispersion forces or dipole–dipole interactions. This initial study forms the basis for future applications requiring tailored mechanical properties.Item Quest for zeolite-like metal-organic frameworks: on pyrimidinecarboxylate bis-chelating bridging ligands(American Chemical Society, 2008) Sava, Dorina F.; Kravtsov, Victor Ch.; Nouar, Farid; Wojtas, Lukasz; Eubank, Jarrod F.; Eddaoudi, MohamedTwo novel porous zeolitelike metal−organic frameworks (ZMOFs) were constructed via the single metal ion-based molecular building block approach from rigid and directional tetrahedral building units and pyrimidinecarboxylate bridging ligands; their ion exchange and hydrogen sorption properties were evaluated.