Collaborative Research: Chemomechanical Transduction in Charge-Transfer Assemblies: Recognition, Binding, and Sensing

About This Grant

With the support of the Chemical Mechanism, Function, and Properties Program of the Division of Chemistry, Professor Pavel Anzenbacher of the Department of Chemistry at Bowling Green State University and Professor Mark A. Olson of the Department of Physical and Environmental Sciences at Texas A&M University-Corpus Christi are studying how to transform simple one-dimensional molecules into complex three-dimensional structures that function as chemical sensors. This project will create new molecular receptors that recognize and bind biologically and pharmacologically relevant substances and convert this recognition into a mechanical response — a process known as chemomechanical transduction — that is visibly detectable. This research will advance our fundamental understanding of how molecules recognize each other and change shape upon binding, knowledge that can be applied to develop new diagnostic tools and smart materials useful in health, chemical monitoring, and security applications. The project also provides rich educational opportunities where undergraduate and graduate students will participate in cutting-edge photochemistry experiments and receive mentorship in research. Through new course-based undergraduate research experiences and summer internships between the two universities, the team will train a cohort of young scientists in advanced chemical techniques and inspire them to pursue STEM careers and graduate programs. The team will synthesize extended viologen-like host oligomers with precisely defined lengths and functional groups using solid-phase chemistry. These electron-poor, cationic hosts will be decorated with fluorescent dyes to enable optical signaling. The hosts are designed to bind electron-rich aromatic guest molecules (for example, indole-based neurotransmitters like serotonin or related drug compounds) through charge-transfer interactions. Upon guest binding, the flexible one-dimensional host strands will fold or aggregate into ordered molecular assemblies, effectively converting from 1D to 3D structures. This binding-induced conformational change — a form of chemomechanical transduction — will bring the attached dyes into proximity, triggering a fluorescence resonance energy transfer (FRET) turn-on signal or aggregation-induced emission. If the guest molecule is chiral, it is expected to twist the host-guest assembly into a helical form, yielding a detectable chiroptical signature such as circularly polarized luminescence (CPL). The researchers will use a broad array of spectroscopic and analytical techniques to investigate these phenomena: for example, time-resolved fluorescence measurements will quantify FRET efficiency, nuclear magnetic resonance (NMR) spectroscopy (including 2D NMR and diffusion-ordered spectroscopy) will elucidate the structure and dynamics of the complexes, and isothermal titration calorimetry will determine binding strengths and thermodynamic parameters. By correlating the host length and structure with its optical and chiral responses upon guest binding, this study will reveal fundamental principles governing supramolecular recognition and assembly. The outcomes will advance knowledge in the photochemistry and physical chemistry of supramolecular systems and lay the groundwork for innovative sensor technologies for chemical analysis and molecular sensing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.