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- Title
- The synthesis of bis(dimolybdenum)-1,3,5,7-tetrakis(2-pyridylimino) benzodipyrrole as a precursor for an inorganic, quadruple bond containing polymer.
- Creator
- Kavanaugh, David John, Florida Atlantic University, Baird, Donald M., Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
- Abstract/Description
-
The planar, dinuclear, tridentate ligands, 1,3,5,7-tetrakis(2-pyridylimino)benzodipyrrole (TAII) and 1,3,5,7-tetrakis(4,6-dimethyl-2-pyridylimino)benzodipyrrole (DiMeTAII) were synthesized and characterized as were all intermediates characterized by both infrared and 1H-NMR spectra. Evidence is presented for the formation of Mo4(OAc)6-(DiMeTAII) (I), the dinuclear analog of Mo2(OAc)3-BAII using UV/Vis to show the delta--->delta* transition typical of the quadruple bond and for the...
Show moreThe planar, dinuclear, tridentate ligands, 1,3,5,7-tetrakis(2-pyridylimino)benzodipyrrole (TAII) and 1,3,5,7-tetrakis(4,6-dimethyl-2-pyridylimino)benzodipyrrole (DiMeTAII) were synthesized and characterized as were all intermediates characterized by both infrared and 1H-NMR spectra. Evidence is presented for the formation of Mo4(OAc)6-(DiMeTAII) (I), the dinuclear analog of Mo2(OAc)3-BAII using UV/Vis to show the delta--->delta* transition typical of the quadruple bond and for the determination of percent molybdenum which is consistent with the proposed structure. A review of recent studies into the field of quadruply bonded metal containing polymers will be discussed along with application of compound (I) in this field.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14950
- Subject Headings
- Ligands (Biochemistry), Metal-metal bonds, Diffusion bonding (Metals)
- Format
- Document (PDF)
- Title
- Dependence of spectroscopic and electrochemical properties of dimolybdenum multiimine complexes on ligand structure.
- Creator
- Yang, Fengli, Florida Atlantic University, Baird, Donald M.
- Abstract/Description
-
The complexes MoX4(Multiimine)2, where X = Cl, Br, I and Multiimine = dimethyl-bipyridine, bipyridine, phenanthroline, bipyrazine, bipyridazine and bipyrimidine, have been prepared. The product complexes apparently contain non-bridged quadruple molybdenum-molybdenum bonds. Each molybdenum is coordinated to a bidentate diimine and two halogen atoms. An electronic absorption study reveals an important trend that the intensity of the delta-->delta* transition increases with decreasing energy....
Show moreThe complexes MoX4(Multiimine)2, where X = Cl, Br, I and Multiimine = dimethyl-bipyridine, bipyridine, phenanthroline, bipyrazine, bipyridazine and bipyrimidine, have been prepared. The product complexes apparently contain non-bridged quadruple molybdenum-molybdenum bonds. Each molybdenum is coordinated to a bidentate diimine and two halogen atoms. An electronic absorption study reveals an important trend that the intensity of the delta-->delta* transition increases with decreasing energy. This shows the energy of this band is determined by mixing of this transition with a metal-to-ligand charge transfer transition. An EEC type mechanism is proposed for the redox behavior of these compounds on the basis of an electrochemical study and some consistent results are obtained by correlating the oxidation potentials with the delta-->delta* transition energies. Also, fairly good correlations of both the delta-->delta* transition energies and the oxidation potentials with pk(a) of L are obtained.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14724
- Subject Headings
- Molybdenum, Diffusion bonding (Metals), Ligand binding (Biochemistry)
- Format
- Document (PDF)
- Title
- Investigation of debonding and crack kinking in foam core sandwich beams.
- Creator
- Prasad, Srinivas., Florida Atlantic University, Carlsson, Leif A., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
Debond failures in structural sandwich may lead to severe reductions in load-bearing capability of the structure because of impartial transfer of shear and tensile forces between facing and core due to the lack of interfacial bonding. Analysis of interfacial bonding in sandwich specimens subjected to transverse tensile and shear forces is presented. Stress intensity factors computed based on the near-tip displacement field are related to experimental crack growth observation on the sandwich...
Show moreDebond failures in structural sandwich may lead to severe reductions in load-bearing capability of the structure because of impartial transfer of shear and tensile forces between facing and core due to the lack of interfacial bonding. Analysis of interfacial bonding in sandwich specimens subjected to transverse tensile and shear forces is presented. Stress intensity factors computed based on the near-tip displacement field are related to experimental crack growth observation on the sandwich beams with aluminum skins on a wide range of PVC foam cores. Experimentally it was found that the crack tends to grow at the interface between the bondline and core as opposed to skin/bondline interface. In shear dominated fields, a pre-existing flow tended to deflect into the core rather than grow along the interface. The tendency for kinking and the direction of the kink is examined experimentally and analyzed using the finite element method.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14861
- Subject Headings
- Finite element method, Sandwich construction, Diffusion bonding (Metals), Fracture mechanics
- Format
- Document (PDF)
- Title
- Local buckling and debond propagation in sandwich columns and panels.
- Creator
- Aviles, Francis., Florida Atlantic University, Carlsson, Leif A., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The local buckling failure mechanism and subsequent debond propagation in sandwich columns and panels with composite face sheets containing a face-to-core debond is experimentally, analytically, and numerically analyzed. The experimental investigation is based on a comprehensive test program to examine local buckling failure and fracture toughness of sandwich specimens consisting of glass/epoxy face sheets over various density PVC foams and a balsa wood core. Elastic foundation and finite...
Show moreThe local buckling failure mechanism and subsequent debond propagation in sandwich columns and panels with composite face sheets containing a face-to-core debond is experimentally, analytically, and numerically analyzed. The experimental investigation is based on a comprehensive test program to examine local buckling failure and fracture toughness of sandwich specimens consisting of glass/epoxy face sheets over various density PVC foams and a balsa wood core. Elastic foundation and finite element models are developed for prediction of the local buckling load of sandwich columns and panels containing an implanted debond at the face/core interface. Nonlinear finite element analysis was conducted to investigate debond propagation in the post-buckling region. Overall, model predictions were in agreement with experimental results. The buckling load was found to decrease with reduced face sheet stiffness, reduced core modulus, and increased debond length. Sandwich panels with circular debonds were more resistant to local buckling than those with square debonds of the same characteristic size. Circular debonds of 50 mm diameter and square debonds of 45 mm side length established the threshold for local buckling failure. Nonlinear finite element analysis of debonded sandwich columns and panels showed that the major crack displacement is opening (mode I). The tendency of the crack tip to first open and then close after buckling of the face sheet is believed to be due to the formation of an eccentric load path at the onset of buckling. The fracture mechanics analysis of debonded sandwich panels showed that the energy release rate is much higher in the direction perpendicular to the applied load than along the loading direction, and exceeds the measured toughness value in the transverse direction. This explains the experimental observation that a debond embedded in a sandwich panel tends to propagate in the transverse direction.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fau/fd/FADT12123
- Subject Headings
- Buckling (Mechanics), Sandwich construction, Fracture mechanics, Diffusion bonding (Metals), Strength of materials
- Format
- Document (PDF)