Synthesis and characterization of supramolecular porphyrin and porphyrazine photonic materials and synthesis of a covalent base pair of DNA

Part A: Porphyrins linked directly to the 4,4' or 5,5' positions of 2,2'-bipyridine: A new supramolecular building block and switch. The synthesis and coordination chemistry of two porphyrin dimers linked either at the 5,5 ' or the 4,4' positions of 2,2' bipyridine is described. These compounds, which may serve as a molecular tectons for the constructions of a variety of supramolecular arrays of diverse function, reveal that the ground- and excited-state electronic communication between the chromophores is only moderately affected by the complexation state of the bipyridyl moiety. The nature of the metal ion chelated by the bipyridine only slightly perturbs the ground state spectra and differences observed in the excited state are largely ascribed to the heavy atom effect. This investigation also shows that conformational changes in structural subunits, in this case, induced by bipyridyl complexation of various metal ions, do not necessarily require reorganization supramolecular systems.; Part B: Hierarchical self-assembly of photonic materials: Synthesis and characterization of porphyrazine-porphyrazine dimers and porphyrazine-porphyrin tetramers. The 2,3-bis(dimethylamino or diamino)-7,8,12,13,17,18-hexakis(4-(tert-butyl)phenyl) porphyrazine has been prepared via mixed Linstead macrocyclization in good yield. The synthesis and coordination chemistry of the porphyrazine dimers via square planar metal ion linkers are described. The structures of the dimers were characterized by 1H NMR, Electrospray and MALDI mass spectrometry. The photophysical profiles of the dimers were evaluated by means of absorption and emission spectroscopy. This investigation also shows that the supramolecular tetramers consisting of two different chromophores (porphyrazine and porphyrin) can be self-assembled in solution by coordinating the appropriate transition metal ions bearing multitopic ligands. These molecules will serve as part of a library of building blocks for the self-assembly of nanoscale photonic materials.; Part C: Synthesis and characterization of a covalent base pair of DNA. The molecular modeling techniques let Leslie E. Orgel and coworkers propose the design and synthesis of a covalent base with the hydrazone bond linker between two aromatic systems. They claimed the geometry of the covalent base pair is very close to that for the DNA double helix and suggested a double helix containing this covalent base pair should be stable. However, the synthesis of these analogues and starting materials is only heuristically outlined. These compounds are of general interest to research in the field of nucleic acid structure and the mechanisms of nucleic acid unwinding. We report a detailed synthesis of a similar analogue of the covalent base pair and expect similar biochemical properties to those reported by Orgel et al., which will be investigated by a cooperative biochemistry group.