Structure-Function Relations: Modeling Mega-Stokes Shifts
Conference Year
January 2020
Abstract
Stokes shift is a critical metric of photophysical properties. A molecule’s Stokes shift is the energy difference between the lowest wavelength of light it absorbs and the lowest wavelength of light it emits. Small Stokes shifts allow for self-quenching, a phenomenon by which compounds immediately reabsorb the light they emit. Self-quenching is of great significance to industrial and commercial applications for it effectively negates a molecule’s ability to produce usable light. Conversely, large Stokes shifts are highly desirable for they indicate an inhibition of self-quenching. The Stokes shifts of [1,2,3]triazolo[1,5-a]pyridinium (TOP) and [1,2,3]triazolo[1,5-a]quinolinium (TOQ) dyes are so extraordinarily large that they have been dubbed Mega-Stokes shifts. To investigate this phenomenon, computational chemistry, particularly time-dependent density functional theory (TDDFT), was used to model the photophysics of TOP and TOQ dyes. Low-level computations proved poor predictors of empirically known constants, but more complex long-range calculations have yielded very accurate models. This has allowed for study of the relationship between the dyes’ conformational and electronic structures which is hypothesized to be key to the generation of a Mega-Stokes shift. Understanding the mechanisms underlying the TOP and TOQ dyes’ exceptional photophysical characteristics provides a lead into synthesizing new materials with Mega-Stokes shifts.
Primary Faculty Mentor Name
Matthew Liptak
Graduate Student Mentors
Morgan Cousins
Faculty/Staff Collaborators
Matthew Liptak (Primary Investigator), Morgan Cousins (Graduate Student Mentor)
Status
Undergraduate
Student College
College of Arts and Sciences
Program/Major
Chemistry
Second Program/Major
Mathematics
Primary Research Category
Engineering & Physical Sciences
Structure-Function Relations: Modeling Mega-Stokes Shifts
Stokes shift is a critical metric of photophysical properties. A molecule’s Stokes shift is the energy difference between the lowest wavelength of light it absorbs and the lowest wavelength of light it emits. Small Stokes shifts allow for self-quenching, a phenomenon by which compounds immediately reabsorb the light they emit. Self-quenching is of great significance to industrial and commercial applications for it effectively negates a molecule’s ability to produce usable light. Conversely, large Stokes shifts are highly desirable for they indicate an inhibition of self-quenching. The Stokes shifts of [1,2,3]triazolo[1,5-a]pyridinium (TOP) and [1,2,3]triazolo[1,5-a]quinolinium (TOQ) dyes are so extraordinarily large that they have been dubbed Mega-Stokes shifts. To investigate this phenomenon, computational chemistry, particularly time-dependent density functional theory (TDDFT), was used to model the photophysics of TOP and TOQ dyes. Low-level computations proved poor predictors of empirically known constants, but more complex long-range calculations have yielded very accurate models. This has allowed for study of the relationship between the dyes’ conformational and electronic structures which is hypothesized to be key to the generation of a Mega-Stokes shift. Understanding the mechanisms underlying the TOP and TOQ dyes’ exceptional photophysical characteristics provides a lead into synthesizing new materials with Mega-Stokes shifts.