Bazan Group Research Interests

University of California at Santa Barbara

	Research Projects: Click images for more information Organometallic Initiators for Controlled Polymerization Reactions Our group is interested in providing a variety of synthetic options for polymer chemists interested in the controlled synthesis of polyolefins with unique structures and/or functionalities. Much of the effort concerns the development of well-defined organometallic species that carry out the reaction of interest. For example, we reported the tandem polymerization approach to synthesizing branched polyethylene by combining the concurrent action of three different initiators.
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	Key to the success of the triple tandem scheme is the successful design of nickel initiator systems that can control the oligomerization of ethylene to either 1-butene or a distribution of higher molecular weight oligomers. Current research is centered on the design of polymerization initiators that allow the copolymerization of ethylene with functionalized monomers. One such initiator system is shown below

	The initiator produced by the combination of nickel organometallic complexes allows the synthesis of polymers with structures that contain two segments of very different polarity and structural properties.

	2. Organic Semiconductors We are pursuing several areas of research involving organic semiconductors, that is organic materials, which show semiconducting properties We are pursuing several areas of research involving organic semiconductors, that is organic materials, which show semiconducting properties and which may serve as components in several emerging technologies. Our approach takes advantage of strong synthetic expertise. In many circumstances we aim to design, or “engineer”, at the molecular level properties that become manifest at the bulk level. Understanding how optoelectronic properties evolve from molecules to the ensemble encountered in solids is a primary challenge. In one area of research, we are interested in developing the science and applications of conjugated polyelectrolytes. Conjugated polyelectrolytes are defined as polymers having a backbone with a p-delocalized electronic structure and pendant groups with functionalities capable of ionizing in a high dielectric medium such as water. The properties in solution and in the solid state of these materials are difficult to predict a priori from simple molecular structure considerations since they combine the well-known complexity of polyelectrolytes, for which physicochemical properties depend on variable long-range electrostatic interactions, with the rigid and highly hydrophobic nature of conjugated polymers. Furthermore, when considering applications in organic optoelectronic devices, such as solar cells, light emitting diodes (LEDs) and thin film transistors (TFTs), one needs to consider and control interchain arrangements and contacts since these determine charge mobility, charge injection and emission quantum yields. One Specific application of sonjugated polyelectrolytes is in the optical amplification of fluorescent assays which betray the presence of harmful organisms in the environment or can be used to very quickly obtain genetic information. The function of a homogenous assay is schematically described below We are pursuing sever

	Conjugated polyelctrolytes can also be ued to simplify the operation of DNA chips and microarray detection of DNA sequences (Methods For Strand-Specific DNA Detections With Cationic COnjugated Polymers SUitable For Incorporation Into DNA Chips And Microarrays, Liu, B.; Bazan, G.C. Proc. Nat. Acad. USA 2005

	Conjugated polyelectrolytes ofer unique options for the fabrication of optoelectronic devices, such as organic light emitting diodes and solar cells. The main practical advantage is that it is possible to cast multiple layers or organic materials from solvents of very differnt polarities (i.e. methanol or water vs. toluene). Alternating solubility characteristics make it possible to not disturb underlying layers.

	In a new research direction, we are investigationg the effects of incorporating metal nanparticles with organic devices. We anticipate two possible functions of the metal compnent. One is that plasmon/transitoin moment coupling will lead to shorter radiative lifetimes of triplet emitters and thereby imporve the efficiency of the most advanced organic emitting devices. Secondly, field enhancement by action of the metal compenent should lead to an improvement of solar cell efficiencies.

	For futher information on any of the research presented here please feel free to contact Gui Bazan at bazan@chem.ucsb.edu

Professor Bazan