LSU

The general theme of the research that is carried out in our laboratories is the chemistry of supramolecular systems in solution and on surfaces.  Our desire is to be able to control the properties of materials by manipulating the structure of the materials on the molecular scale.  

For instance, our group is interested in constructing stimuli-sensitive molecular architectures based on dendrimers, surfactants, and polymers that can be used to trap, contain, and release molecules; through the use of redox-responsive and temperature-responsive functionalities at the exterior of dendrimers, we are able to regulate the transport of materials from the interior of the dendrimer to the exterior, surrounding solution.  In addition, other redox-responsive or temperature-responsive moieties can be placed on a variety of materials for use in chemical sensing applications; see a recent Chemical and Engineering News article highlighting our work in this area. This NSF-funded project involves the use of a variety of analytical methods, such as NMR methods, fluorescence spectroscopy, and infrared spectroscopy, and synthetic strategies for making the host systems. Recent results indicate that such materials will be useful in the delivery of molecules in the body and in miniaturized analytical systems. In addition, we have been exploring the properties of the stimuli-responsive moeities using MALDI-MS, in particular, their end groups and molecular weight.

In another area, we are interested in controlling the surface properties of polymer substrates used in the fabrication of microanalytical devices by immobilizing nanometer-thick layers of organic and biological molecules on the surface of the plastic substrate; such surface modification protocols are of great importance to microanalytical devices geared towards genomic, proteomic, and environmental analyses.  This project is funded through the National Institutes of Health and NSF and is a collaborative effort with the Soper Group in Chemistry, as well as groups in Mechanical Engineering.  In addition, we are working with several groups in physics, biology, and engineering to build nanoscopic sensors and pumps/actuators.

In addition to these more applied directions, we are interested in understanding the fundamentals of adsorbate interactions (alkanethiols, isocyanides) with metal surfaces (Pt, Au, Ag, Cu) and the interactions of metals (evaporated, electrolessly deposited, nanoclusters) with "sticky" (chemically modified so as to present a binding ligand to the depositing metal) surfaces.  For example, we are looking at ways to photopattern surfaces so that metal deposition is confined to a given area (micrometer to nanometer square areas).  Both areas are of interest to the microelectronics industry, as well as the microanalytical device and sensor communities.  

Related to this binding of metals on surfaces is the template-assisted formation of metal nanoclusters using dendrimers as the template.  We have recently shown that ~1 nm diameter Cu nanoclusters can be made by reduction of Cu(II)-amine-dendrimer complexes.  By varying the Cu(II):dendrimer ratio, we have been able to make extremely monodisperse metal and metal oxide nanoclusters.  This work will be used to lay the groundwork for future studies of bi-metallic clusters and metal oxide nanoparticles that can be used for catalysis applications, including those associated with environmental concerns.

Students within the McCarley Group gain a great deal of experience in a number of areas in chemistry, biology, and materials science due to the diverse, interdisciplinary nature of the research efforts.  For example, you are apt to find someone doing organic synthesis on a surface or solution one day, and then discover them carrying out surface infrared spectroscopy, scanning probe microscopy, X-ray spectroscopy, or mass spectrometry the next day!  Or you might find someone making a microdevice, and then a few minutes later see that they are performing photopatterning of the plastic surface to immobilize proteins or DNA. Thus, the student who carries out research in the McCarley Group will become well-versed in a variety of topics related to analytical, physical, inorganic, macromolecular, biological, and organic chemistries.