Fogged direct-positive silver halide emulsion containing a cyanine dye having an indole or indolenine nucleus substituted with a benzoyl or a phenylsulfonyl group
AssigneeMinnesota Mining and Manufacturing Company
InventorsPaolo Beretta, Luigi Valbusa
Life of this patent
Estimating the term…
Abstract
New cyanine dyes, comprising at least one of the following nuclei (or derivatives thereof): 1. 2,3,3-trimethyl-5-phenyl-sulfonyl-indolenine; 2. 2,3,3-trimethyl-5-benzoyl-indolenine; 3. 1-aryl or alkyl-2-phenyl-5-phenyl-sulfonyl-indole; 4. 1-aryl or alkyl-2-phenyl-5-benzoyl-indole, Are desensitizers for silver halide negative emulsions and useful electron acceptor spectral sensitizers for direct positive silver halide emulsions.
Claims6
A light-sensitive, fogged direct positive silver halide emulsion characterized in that it contains a sensitizing amount of cyanine dye corresponding to one of the following formulae:
- ##STR55## wherein:
- m represents a positive integer of from 1 to 2;
- n represents a positive integer of from 2 to 4;
- R, r.sub.6 each represent a benzoyl group or a phenylsulfonyl group;
- R.sub.1, r.sub.1 ',
- r.sub.2 and R.sub.7 each represent a substituted or non-substituted acyclic hydrocarbon substituent;
- an alkyl-aryl substituent or an aryl substituent;
- R.sub.3 represents an aryl or substituted aryl group;
- R.sub.4 represents an hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an aryl group, a thienyl group, with the proviso that at least one of the two substituents R.sub.4 is an hydrogen atom;
- R.sub.5 represents an hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an halogen atom, a nitro group, a benzoyl group or a phenylsulfonyl group;
- R.sub.8, r.sub.9 each represent an alkyl group containing from 1 to 4 carbon atoms;
- X.sup.- represents an acid anion;
- and
- Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, said non-metallic atoms being selected from the group consisting of carbon, oxygen, sulfur, nitrogen, and selenium atoms.
Dependencies are inferred from the claim text.