Dominick J. Casadonte, Jr.

Minnie Stevens Piper Professor

 

Ph.D., Purdue University, 1985

Postdoctoral Study, University of Illinois

Dreyfus Foundation Scholar/Fellow, 1988-1989

Fulbright Senior Scholar (France), 2000
 

 

 

Phone: (806) 742-1832

Fax: (806) 742-1289 

Inorganic and Materials Chemistry

Professor Casadonte’s research interests focus upon the dynamics of unusual excited state processes as well as the fabrication of novel molecular systems with potential applications as molecular photodevices. Several areas of research in his lab are aimed at understand the chemistry and physics of these high-energy events.

• The Chemical Effects of High-Intensity Ultrasound

Acoustic cavitation produces temperatures in excess of 5000 K and pressures greater than 100 atmospheres during the adiabatic collapse of gas vacuoles in solution. These physical extremes are used to produce high-energy species not available by analogous thermal or photochemical routes. Sonication of mixed-metal powders in hydrocarbon solvents leads to the formation of intermetallic coatings which may have use as dehydrogenation catalysts and in thin film coatings. Ultrasound is also an effective means of removing hydrocarbon contaminants from aqueous media. This process may prove effective in the environmental remediation of waterborne pollutants. We have, for example, been able to degrade 1500 ppm of decane in water to CO2, H2, and H2O in slightly more than one hour.


Figure 1. The sonolytic degradation of octane and decane in water.

The spring semester of 2000 was spent in Chambery, France on a Fulbright Scholarship. While there, Dr. Casadonte began preliminary studies on the application of pulsed ultrasound to enhance sonochemistry. It was found that with the appropriate pulsed waveform an enhancement of more than 300% in the rate of degradation of environmentally contaminants could be achieved relative to continuous ultrasonic irradiation. Little is known about the interaction of the pulsed sound field with the chemical species involved. Our group is also interested in exploring non-linear cavitation processes using variable frequency and heterodyne ultrasound. In this case, two different ultrasonic frequencies are input which produce a third frequency which is non-resonant with the cavitation sites. It is our belief that the non-linear cavitation phenomena produced by the multi-frequency ultrasound will lead to enhancements in the rate and efficiency of cavitation.

Our other activities involving sonochemistry include the fabrication of metal phosphide semiconductor materials from organometallic precursors, generation of graphite intercalation compounds, and a facile sonochemical methodology for the formation of ionic liquids. We have also been developed a single-transducer variable frequency sonicator which allows our group to probe the effect of frequency on sonochemical activity in a systematic manner.
 
 

Figure 2. The Variable Frequency Sonicator.



• Supramolecular Chemistry and the Design of Photoactive Metallopolymers

The goal of this research is an understanding of the spatial characteristics required for the fabrication of molecular photodevices. We have recently developed the first examples of photoactive multinuclear Cu(I) complexes containing bridging phosphines. We have also prepared multinuclear Cu(I) complexes containing phenanthrolines bound via oxyben bridges.


Figure 3. Crystal structure of [(PPh3)2Cu(dmp)-O-(dmp)Cu(PPh3)2]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline)
Similar complexes have been catenated to form metallo-polymers possessing photo-induced charge-storage capacity. Our research group has recently synthesized a unique Cu(I) metallopolymer using polymerized phenanthroline acrylate as the ligand. We have synthesized a double helical species containing two phenanthroline units per Cu(I) (generating a Cu(I) channel in the middle of the polymer), and an asymmetric system containing one phenanthroline ligand and two coordinated triphenylphosphine ligands per copper. The polymer has photocapacitive characteristics, with measurable photocapacitance under 354 nm irradiation of approximately 65 µF/g (~600 mF/mole or 1.3 mF/m2). The mononuclear species displays no analogous photcapacitance. Metallopolymers of this type may have future applications in optical computing.

• Photochemistry/Photophysics

Another aspect of Professor Casadonte’s research includes the synthesis of complexes which display simultaneous emission from two or more distinct excited states. He has recently prepared a series of Cu(I) complexes containing phosphine sulfide ligands which emit from both charge transfer and intraligand emission excited states. Density functional calculations are currently underway in an attempt to understand the mechanism of multistate luminescence from these systems, which violate Kasha's rule.
 
 

Figure 4. Luminescence Spectra of Cu(I) Phosphine and Phosphine Sulfide Complexes


Presentations, Funding, Recent Awards/Honors, Research Students

Fall 2005, CHEM 1307-H, Syllabus

Fall 2005, CHEM 1307-H, Homework 1
 

 Selected Publications

  • "Enhancing Sonochemical Degradation of Environmental Contaminants Using Power-Modulated Pulsed Ultrasound: An Initial Study“, Casadonte, Jr., D.J.; Petrier, C.; Flores, M. Ultrasonics Sonochemistry, 2005, 12(3), 147-152.

  •  "Facile Sonochemical Synthesis of Graphite Intercalation Compounds“, Jones, J. E.; Cheshire, M. C.; Casadonte, Jr., D.J.; Phifer, C.C. Org. Letts. 2004, 6(12), 1915-1917.

  • "Photobleaching Comparison of Poly(methylphenylsilylene) and Poly(phenylsilyne)" Thomes Jr., W.J.; Simmons-Potter, K.; Phifer, C.C.; Potter Jr., B. G.; Jamison, G.M.; Jones, J.E.; Casadonte, Jr., D.J. J. App. Phys. 2004, 96(11),  6313-6318.

  • "Methanol Electrochemical Oxidation at Nanometer-Scale PtRu Materials“, Korzeniewski, C.; Basnayake, R.; Vijayaraghavan, G.; Li, Z.; Shanhon, X.; Casadonte, D.J. Surface Sci. 2004, 573 (1), 100-108.

  • 'The Use of Pulsed Ultrasound Technology to Improve Environmental Remediation: A Comparative Study" Casadonte, Jr., D.J.; Flores, M.; Petrier, C. Environmental Technology 2004, Accepted for Publication.

  • "Variable Frequency Sonochemistry I: Design of a Variable Frequency Sonicator“, Wayment, D.G.; Casadonte, Jr., D.J. Ultrasonics: Sonochemistry 2002, 9(4), 189-195.

  • "Variable Frequency Sonochemistry II: Frequency Dependence of the Sonochemical Degradation of Alachlor“, Wayment, D.G.; Casadonte, Jr., D.J. Ultrasonics: Sonochemistry 2002, 9(6) 251-257.

  • "Sonochemical Synthesis of Iron Phosphide“, Sweet, J.D.; Casadonte, Jr., D.J. Ultrasonics: Sonochemistry 2001, 8, 97-101.

  • "Crystal Structure and Emission Study of [(PPh3)2Cu(dmp)-O-(dmp)Cu(PPh3)2]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline)“, Lu, J.; Whittlesey, B.R.; Casadonte, Jr., D.J. Journal of Chemical Crystallography 1999, 29(7), 797.

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