A series of highly organic -solu ble [ bis( tria I kylsi loxy) ] si I ico n tetra kis (a I ky It h io) -2,3nap ht halocya n i neshave been synthesized, and their 'H NMR, electronic absorption and fluorescence spectra measured. These spectra indicate that ( R',SiO),SiNc(SR2), are monomeric in solution (10-2-10-7 mol dm-,). In their solid films, all Q-band absorption maxima of ( R1,Si0),SiNc(SR2), are red-shifted from their monomeric Q-band maximum. The extent of shift significantly increases with decreasing R' length of the axial substituents, but the effect is far less with ring substituents, R2. These observations are clearly explained using the exiton model. Our results indicated that novel naphthalocyanine ( R',SiO),SiNc(SR2), molecules have a J-type molecular arrangement in thin solid films.* It is well known that J aggregates exhibit spectral red shifts (probably 'J' for Jelley, one of the lirst workers to investigate thcsc shifts), whereas the blue-shifted aggregates are designated iis 'H'aggregates ( H for hypsochromic).
2,8-Dimethoxycarbonyl, 8-methoxycarbonyl, and 2,8-dimethyl derivatives of bicyclo[3.2.1]octa-3,6-diene gave 4-imino-1,4-dihydropyridines and pyrroles under acidic conditions. In addition, the C6–C7 dihydro-analogue produced 2-vinylpyrrole by the methyl carbamate elimination.
212ChemInform Abstract The 2,8-diazabicyclo(3.2.1)octadiene (Ia) is rearranged upon treatment with acids to give the pyrroles (IV) and (V), together with the dihydropyridine (III). A mixture of (III) -(V) is also obtained from the N-methoxycarbonylimine (VI). Silylation of (Ia) yields the N-pyrrolylvinyl O-silyl carbaminate (II). Reduction of the diester (Ia) produces the dimethyl derivative (Ib) which is converted tothe dihydropyridines (VII) or (VIII). The diazabicyclooctene (IX) forms the pyrrole (X) when heated in the presence of p-toluenesulfonic acid.
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