Part I. Effects of Pyramidalization at Nitrogen In a Series of Donor-Pi-Acceptor Dyes Part II. Effects of Vinyltrimethoxysilane on Bone Growth Templates.

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Robinson, Matthew Allen
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Middle Tennessee State University
Part I. Several methods have been developed to synthesize and optimize the parameters for organic materials that display nonlinear optical (NLO) properties. To determine the effect of donor group geometry on stability and conjugation in donor-pi-acceptor polyenes, compounds 1-8 were synthesized and characterized. Dyes were characterized with UV/Vis, IR, HRMS, and 1H/13C NMR spectroscopy. UV and 1H NMR solvatochromism (in a wide range of solvents) was correlated with the pi* polarity scale and NMR coupling constants were related to bond length alternation. It was found that dyes containing a thiobarbituric acid acceptor showed better solubility, linear positive UV solvatochromism when plotted against the solvent pi* polarity, and exhibited solvatochromic trends in NMR. Dyes containing a tricyanofuran acceptor had poor solubility, increased solvent sensitivity in UV studies, and limited 1H NMR information due to peak overlap. Results were supported with geometry calculations using B3LYP and HF methods.
Part II. A vast amount of research has been conducted to understand the mechanisms of bone degeneration as well as methods to promote bone growth. Mesoporous silicate (m-SiO2) foams are biocompatible, have comparable pore size to bone, and are conducive to growth of bone-forming cells, osteoblasts. However, they lack the required mechanical strength for application as regenerative scaffolds. To increase crosslinking and flexibility during the foam template coating process, vinyl trimethoxysilane (VTMS) was incorporated into the sol-gel coating. Polyurethane foams were iteratively dip-coated with sol-gel, irradiated with a 450 W UV lamp and then air-dried to give 1-12 layer materials. The foams were calcined at 600 oC in a Lindberg furnace to remove the organic component, resulting in an inorganic scaffold. The materials were analyzed using SEM images including an analysis of the effect of drying time and VTMS content on pore sizes. Statistically, the data showed minimal differences between samples containing VTMS and those without the cross-linker.