{"doi":"10.1002/ejoc.202200270","title":"Structure‐Activity Studies of Nitroreductase‐Responsive Near‐Infrared Heptamethine Cyanine Fluorescent Probes","abstract":"Two new classes of near-infrared molecular probes were prepared and shown to exhibit \"turn on\" fluorescence when cleaved by the nitroreductase enzyme, a well-known biomarker of cell hypoxia. The fluorescent probes are heptamethine cyanine dyes with a central 4'-carboxylic ester group on the heptamethine chain that is converted by a self-immolative fragmentation mechanism to a 4'-caboxylate group that greatly enhances the fluorescence brightness. Each compound was prepared by ring opening of a Zincke salt. The chemical structures have either terminal benzoindolinenes or propargyloxy auxochromes, which provide favorable red-shifted absorption/emission wavelengths and a hyperchromic effect that enhances the photon output when excited by 808 nm light. A fluorescent probe with terminal propargyloxy-indolenines exhibited less self-aggregation and was rapidly activated by nitroreductase with large \"turn on\" fluorescence; thus, it is the preferred choice for translation towards in vivo applications.","journal":"European Journal of Organic Chemistry","year":2022,"id":264986,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":11,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9498,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":923541,"name":"Kirk M. Atkinson","orcid":"0000-0001-9827-1949","position":1,"is_corresponding":false},{"id":923542,"name":"Sai Shradha Reddy Kommidi","orcid":"0000-0001-8024-3237","position":2,"is_corresponding":false},{"id":923543,"name":"Tristan Freel","orcid":"0000-0003-2019-7771","position":3,"is_corresponding":false},{"id":923544,"name":"Hana Janeková","orcid":"0000-0002-2935-3040","position":4,"is_corresponding":false},{"id":923545,"name":"Peter Štacko","orcid":"0000-0002-9404-7269","position":5,"is_corresponding":false},{"id":798978,"name":"Bradley D. Smith","orcid":"0000-0003-4120-3210","position":6,"is_corresponding":false},{"id":923540,"name":"Janeala J. Morsby","orcid":"0000-0002-0700-5969","position":0,"is_corresponding":true}],"reference_count":44,"raw_metadata":null,"created_at":"2026-07-19T00:26:45.905331Z","pmid":"38322783","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}