Hemicyanine push-pull dyes based on chromene electron donors

A method of making a compound, the method comprising the steps of:

• reacting a compound having a structure:
• wherein R1 and R2 are independently hydrogen, halide, C1-C12 alkyl, C1-C12 heteroalkyl, C2-C12 alkenyl, C2-C12 alkynyl, C1-C12 haloalkyl, C2-C12 haloalkenyl, cycloalkyl, heterocycloalkyl, bicyclic cycloalkyl, bicyclic heterocycloalkyl, cycloalkenyl, cycloalkynyl, aryl, or heteroaryl, and
• wherein n is an integer ranging from 0-4;
• with a compound having a structure:
• wherein R3 is hydrogen, halide, C1-C12 alkyl, C1-C12 heteroalkyl, C2-C12 alkenyl, C2-C12 alkynyl, C1-C12 haloalkyl, C2-C12 haloalkenyl, cycloalkyl, heterocycloalkyl, bicyclic cycloalkyl, bicyclic heterocycloalkyl, cycloalkenyl, cycloalkynyl, aryl, or heteroaryl;
• wherein R4 is (C1-C12)—R5, wherein R5 is NR6-8, wherein R6-R8 are independently C1-C12 alkyl;
• sulfonate;
• carboxylic acid;
• amino;
• —C(O)O—R9, wherein R9 is succinimidyl;
• or —NH—C(O)—R10-R11, wherein R10 is C1-C4 alkyl and R11 is maleimide;
• and
• wherein the dashed line (- - - -) denotes an optional ring structure.
• in a condensation reaction to form a compound having a structure:

A method of making a compound, the method comprising the steps of:

• propargylation of a compound having the structure:
• wherein R1 and R2 are independently hydrogen, halide, C1-C12 alkyl, C1-C12 heteroalkyl, C2-C12 alkenyl, C2-C12 alkynyl, C1-C12 haloalkyl, C2-C12 haloalkenyl, cycloalkyl, heterocycloalkyl, bicyclic cycloalkyl, bicyclic heterocycloalkyl, cycloalkenyl, cycloalkynyl, aryl, or heteroaryl,
• into a compound having the structure:
• cyclization in the presence of malononitrile to form a compound having the structure:
• hydrolysis to form a compound having the structure:
• performing an olefination reaction, from 1 to 5 times, to form a compound having the structure:
• wherein n is an integer ranging from 0-4.