Amy Lea Schumacher

Decomposition of Dinuclear Manganese Complexes for the Preparation of Nanostructured Oxide Materials

The crystal structures of several dinuclear complexes of manganese are reported, and the decomposition and analysis of the nanostructured products derived from them are presented. 1,4,7,10-Tetraazacyclododecane (cyclen) forms dinuclear complexes 1-4 containing doubly oxo-bridged or oxo-acetato bridging ligands depending on the manganese salt used for the reaction. Doubly oxo-bridged 1 crystallizes in the orthorhombic space group Pnma, a = 22.3850(14) A, b = 9.1934(5) A, c = 13.2424(10) A, V = 2725.2(3) A(3). 2, containing [Mn(SCN)5](3-) conteranions, crystallizes in monoclinic space group I2/a with a = 18.2699(10) A, b = 11.2384(6) A, c = 18.6432(9) A, alpha = 90.00 degrees, beta = 114.510(6) degrees, gamma = 90.00 degrees, V = 3483.0(3) A(3). Oxo-acetato-bridged 3 crystallizes in orthorhombic space group Pca21, a = 13.9322(11) A, b = 16.2332(13) A, c = 14.6794(8) A, V = 3320.0(4) A(3). Compound 4 consists of a templated quasi-one-dimensional manganese oxalate crystallized in the triclinic space group P1, a = 9.5442(11) A, b = 10.3758(10) A, c = 21.851(2) A, alpha = 83.720(12) degrees, beta = 80.106(13) degrees, gamma = 85.457(13) degrees, V = 2114.9(4) A(3). Compounds 1, 3, and 4 decompose to nanostructured oxide materials, which may be isolated in bulk as lamellar-structured particles or microspheres or deposited on substrates.

Photoinduced electron transfer in a Watson–Crick base-paired, 2-aminopurine∶uracil-C60 hydrogen bonding conjugate

A fluorescent reporter molecule, 2-aminopurine was self-assembled via Watson-Crick base-pairing to a uracil appended fullerene to form a donor-acceptor conjugate; efficient photoinduced charge separation was confirmed by time-resolved emission and transient absorption spectral studies.

Pyren-1-ylmethyl N-substituted oxoporphyrinogens

5,10,15,20-tetrakis(3,5-di-tert-butyl-4-oxocyclohexadien-2,5-yl)porphyrinogen was alkylated at its macrocyclic nitrogen atoms with pyren-1-ylmethyl groups and the effect of increasing N-substitution on the spectroscopic and electrochemical properties was investigated. Both pyrene and oxoporphyrinogen chromophores exhibit fluorescence and there is little interaction between them except in the higher N-substituted compounds. Intra- or intermolecular excimer formation by pyrene is precluded by attachment to the bulky oxoporphyrinogen. Electrochemical measurements revealed reversible redox behavior.