Abstract
Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest.
Highlights
Nitroxides are one of the few families of stable organic free radicals and this feature, together with the remarkable sensitivity of their structure and spectroscopic properties to environmental effects has stimulated their widespread use as spin labels and spin probes in both biological and material chemistry [1,2,3]
In the present paper we have proposed and validated a general and robust strategy providing accurate structures, vibrational and magnetic properties of nitroxide radicals by means of hybrid and double-hybrid functionals in conjunction with suitable basis sets
Anharmonicities and vibrational averaging effects on different properties can be taken into account employing the effective generalized vibrational perturbation theory to the second order
Summary
Nitroxides are one of the few families of stable organic free radicals and this feature, together with the remarkable sensitivity of their structure and spectroscopic properties to environmental effects has stimulated their widespread use as spin labels and spin probes in both biological and material chemistry [1,2,3]. The employed restraints should be at least as accurate as the sought accuracy of the refinement and can be often derived from accurate experimental data available for suitable fragments of the investigated molecular system This approach is seldom exploitable for open-shell moieties, whose accurate structures are usually unknown. Have emerged as the methods of choice for medium- to large-size molecular systems not amenable to the most accurate (and prohibitively expensive) wave-function methods In this connection, several studies have shown that double-hybrid functionals in conjunction with partially augmented triple-zeta basis sets are reliable for geometrical structures, vibrational frequencies and several other spectroscopic properties [7,12,13]. After validating the selected computational approach we provide reference data for a large panel of nitroxides of current interest for biological and/or technological applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
