# Synthesis and Characterization of Nitrogen and Sulfur Donor-Acceptor Stenhouse Adducts

> **NIH NIH R00** · UNIVERSITY OF SOUTHERN CALIFORNIA · 2023 · $88,457

## Abstract

Project Summary/Abstract
 This proposal describes the use of fundamental chemical properties to alter the reactivity of reagents for
the synthesis of biomedically important compounds. Specifically, the chemical properties of C–S bonds will be
used for the synthesis of novel photoswitches named donor-acceptor Stenhouse adducts, DASAs. Though
Stenhouse adducts were introduced in 2014, they have been explored in drug delivery, dynamic phase transfer,
polymers, liquid crystals, selective photoswitching, and chemosensing applications. Despite their promising
applications, DASAs are currently limited by their structural diversity. Only amine donors and two acceptors are
generally used in DASA systems today. As a result, the physical properties and applications are limited.
 The overarching goal is to develop and characterize novel DASA molecules with a narrow HOMO-LUMO
gap such that the newly developed molecules may be activated within the biological window of 650–1450 nm
light. Doing so puts photoswitchable molecules into the realm of challenging photopharmacological and specific
light-emission applications. Specifically, the unique ability for DASA photoswitches to go from linear, uncharged
structures to cyclic, zwitterionic intermediates presents an opportunity to permeate the blood-brain barrier and
to develop interesting thermally activated delayed fluorescence (TADF) species. In order to access new DASA
molecules with the desired characteristics, adducts with sulfur, phosphine, oxygen, and additional conjugation
will be investigated. 2-Thiophenecarboxaldehyde bears a weaker and longer C–S bond in place of the C–O bond
responsible for the inability to incorporate other donor functionality in DASAs when using furfural as a starting
material; thiophene derivatives also carry less electron density on the carbon atoms, making it a perfect substrate
for ring opening upon condensing an acceptor molecule. If the C–S bond is not sufficiently weak, the polarizable
sulfur will be activated using thiophilic Lewis acids. Synthesizing novel Stenhouse adducts 1) provides additional
DASAs to explore applications listed above, 2) enables further research on the chemical properties of these new
photoswitches, and 3) provides an opportunity to develop additional uses like those listed in photopharmacology
and light emission applications.

## Key facts

- **NIH application ID:** 10724739
- **Project number:** 3R00GM140070-03S1
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **Principal Investigator:** Elias Picazo
- **Activity code:** R00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $88,457
- **Award type:** 3
- **Project period:** 2021-01-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10724739

## Citation

> US National Institutes of Health, RePORTER application 10724739, Synthesis and Characterization of Nitrogen and Sulfur Donor-Acceptor Stenhouse Adducts (3R00GM140070-03S1). Retrieved via AI Analytics 2026-07-25 from https://api.ai-analytics.org/grant/nih/10724739. Licensed CC0.

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