title: pH-Elicited Luminescence Functionalities of Carbon Dots: Mechanistic Insights.
abstract: Remarkable and systematic pH-dependent changes are observed in the absorption and emission spectra of carbon dots derived for the first time from lemon juice, a natural bioresource. Detailed photophysical studies of these novel carbon dots (henceforth termed LD), in conjunction with Fourier transform infrared spectra, reveal that among the two possible prototropic equilibria, phenol ↔ phenolate and carboxylic ↔ carboxylate, that occur at the surface of LD, it is the former that is actually coupled with the emissive moiety and directly involved in determining the nature of the electronic energy levels and the associated optical transitions. Apart from providing valuable mechanistic insights on the photoluminescence (PL) of carbon dots, the pH dependence of LD is also demonstrated to yield variable PL signals and perform elementary Boolean logic operations in response to chemical stimulants. The pH effect can therefore complement the optoelectronic functionalities of these promising luminescent nanomaterials and help in the future development of molecular devices and intelligent multianalyte detection systems.
authors.affiliation: Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: Sharmistha
authors.identifier: http://orcid.org/0000-0003-4000-4930
authors.initials: S
authors.lastname: Dutta Choudhury
authors.affiliation: Department of Nanotechnology, Noorul Islam Centre for Higher Education , Kumaracoil, Kanyakumari District, Tamil Nadu 629180, India.
authors.forename: Jiddhu M
authors.initials: JM
authors.lastname: Chethodil
authors.affiliation: Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: Poojan Milan
authors.initials: PM
authors.lastname: Gharat
authors.affiliation: Department of Nanotechnology, Noorul Islam Centre for Higher Education , Kumaracoil, Kanyakumari District, Tamil Nadu 629180, India.
authors.forename: Praseetha
authors.initials: P
authors.lastname: P K
authors.affiliation: Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: Haridas
authors.identifier: http://orcid.org/0000-0002-9295-0198
authors.initials: H
authors.lastname: Pal