Leaps-MPS: unveiling the origin of carbon DOT fluorescence using density functional tight binding

Muhlenberg College received a $192,380 Project Grant from the National Science Foundation (NSF) Division of Chemistry, under the Mathematical and Physical Sciences program (CFDA 47.049), awarded December 1, 2025, with completion by December 31, 2026. The grant supports computational chemistry research to elucidate the mechanisms underlying carbon dot fluorescence through density functional tight-binding (DFTB) simulations. Professor Duchimaza Heredia's research group will investigate the electronic properties of multicolor fluorescence in polymeric and amorphous carbon dots, testing competing hypotheses regarding size-dependent emissions, surface-state derived emissions, and molecular fluorophore mechanisms. The project employs enhanced sampling methods combined with density functional theory (DFT) and DFTB computational approaches to overcome experimental limitations in characterizing carbon dot structures and predicting their fluorescence properties.

Beyond research deliverables, the award funds educational and workforce development initiatives designed to strengthen chemistry education pathways. The project establishes undergraduate research positions for students from diverse backgrounds at Muhlenberg College and creates partnerships with computational chemistry researchers in the Boston area to expose students to graduate-level research environments. Additionally, the award incorporates high school teacher involvement and curriculum integration components to introduce secondary students to computational methods in chemistry research. These combined research and educational outputs address both fundamental scientific questions regarding carbon dots—which have applications in drug delivery, biosensing, and imaging—and broader workforce development objectives in computational chemistry.

Abstract

In this project, managed by the division of chemistry at the NSF, professor duchimaza heredia and students at emmanuel college will use computer simulations to understand why carbon dots fluoresce. Carbon dots are formed by a polymerization reaction of small molecules at high temperatures, and they have been observed to glow in various colors. The multicolor fluorescence of carbon dots makes them useful in applications including drug delivery, biosensing, and imaging. Computational methods will be employed to investigate the reason for fluorescence, overcoming experimental challenges in determining the structure of the carbon dots. This project will create research positions that support training for undergraduate students of diverse backgrounds and establish partnerships with computational chemists around the boston area to introduce students to a graduate-level research environment. The chemistry education pathway will be strengthened by involving high school teachers in this investigation and using aspects of this project to teach high school students how computers are used in chemistry research. Professor duchimaza heredia and his computational chemistry research group will investigate the electronic nature of multicolor fluorescence in polymeric or amorphous carbon dots. Existing hypotheses include size-dependent emissions, surface-state derived emission, and fluorescence due to molecular fluorophores. While fluorescence across the visible spectrum is possible, experimental analysis supports only blue fluorescence. The project will use enhanced sampling methods to predict the structure of amorphous carbon dots. IT will also leverage the chemical accuracy of density functional theory (DFT) and the speed of density functional-based tight-binding (dftb). This project aims to determine whether fluorescence is possible solely due to the carbon DOT structure, identify how the environment of a fluorophore influences its emission properties, and perform extensive benchmarking to compare the results of DFT and dftb for accurate and fast prediction of carbon DOT and fluorophore systems. 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.- subawards are not planned for this award.