Electronic absorption and emission spectral data and fluorescence quantum yields of bridgedp-oligophenylenes, bi- to deciphenyls, and related furans and carbazoles.

Absorption and fluorescence emission spectral data, as well as fluorescence quantum yields (Φf), were determined for 41p-oligophenylene compounds containing 2-6, 8, and 10 benzene rings. Of 29 compounds containing carbon-bridged rings (fluorenes), 28 were dialkylated on each bridge for improved solubility and photostability. Absorption maxima for oligophenylenes were observed at wavelengths as long as 366 nm, emission maxima to 437 nm, and molar extinction coefficients (ɛ) as large as 153,000 L/mol-cm; all three exceeded predicted maximum values for the corresponding unbridged oligophenylenes. The substitution of furan for benzene or carbazole for a fluorene (two examples each) bathochromically shifted absorption and emission maxima. Dialkylated carbon bridges bathochromically shifted absorption and emission maxima, and lowered Φf in biphenyl and in one terphenyl analogue, but appeared to cause no diminution of Φf in higher oligophenylenes. Bis(2-methoxyethyl) substitution on the bridges, incorporated to provide solubility in polar solvents, lowered Φf in all examples. Tertiary alkyl substituents on terminal rings bathochromically shifted the absorption and emission maxima and generally increased Φf. The "loose bolt" effect, which lowers Φf in mononuclear substituted benzenes, may operate in 9,9-dialkylfluorenes, but not in 2,7-di-t-butylfluorene or in higher oligophenylenes. Cyclic ether and methoxy substituents as auxofluors on terminal rings generally bathochromically shifted absorption and emission maxima and increased ɛ and Φf. Cyano substituents bathochromically shifted absorption and emission maxima, and increased ɛ, but lowered Φf slightly.

In vitro antineoplastic activity of C7-substituted mitomycin C analogues MC-77 and MC-62 against human breast-cancer cell lines.

Mitomycin C (MIT-C) is one of the most potent antineoplastic agents used for the treatment of breast cancer and a wide variety of malignant tumors. However, administration of MIT-C is frequently accompanied by the delayed onset of severe myelosuppression We have synthesized a new series of MIT-C analogues that are predicted on a structure/function basis to retain cytotoxicity but exhibit decreased toxicity. These new compounds feature a sugar substitution at the N7 position. Using a series of human breast-cancer cell lines growing in vitro, we determined the structure/activity relationship of two independent N7-substituted spacers displaying the same glucopyranose moiety. N-( [(2-acetamide-3,4,6-tri-O-acetyl-2-deoxy-beta- D-glucopyranosyl)amino]carbonyl] propylmitomycin C (MC-62) contains the sugar moiety linked to MIT-C through a butanoic acid spacer. MC-62 exhibits significantly less biological potency as compared with the parent drug. In contrast, N-[4-(tetra-O-acetylglucopyranosyl)oxy]phenylmitomycin C (MC-77) contains the glucopyranose moiety linked to MIT-C through a phenolic spacer. This analogue generally exhibits greater antitumor activity in vitro as compared with either MC-62 or MIT-C. Thus, N7-substituted analogues containing sugar moieties exhibit altered biological activity, the degree of which is related to the properties/structure of the spacer.