Alkanediyl bridged benzimidazolo monomethine cyanine dyes, processes for their preparation, and photographic emulsions and elements containing such dyes
US4490463A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 3, 1983 |
| Grant date | Dec 25, 1984 |
| Priority date | — |
| Expiry date | Mar 3, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/26
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Alkanediyl bridged benzimidazolo monomethine cyanine dyes are disclosed wherein at least one benzimidazolo nucleus is provided with an electron-withdrawing group. A disclosed preparation of the dyes includes producing an electron-withdrawing group substituted bis(2-nitrophenyl)-2-R.sup.1 -propanediamide, where R.sup.1 is hydrogen or alkyl; converting the nitro groups to primary amine substituents; removing the elements of water to effect ring closure; and thereafter providing the -CR.sup.1 - linked benzimidazole nuclei so formed with an N,N'-alkanediyl bridging group and quaternizing substituents. Dye synthesis is completed by reducing the -CR.sup.1 - linking group to the corresponding methine. The dyes are useful as sensitizers in silver halide emulsions and photographic elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.