DFT Studies on the Molecular Structure, Regioisomerism, Ground and Excited state Charge Transfer Properties of Spiro‐heterocycles. Issue 48 (21st December 2022)

• Record Type: Journal Article
• Authors: C R, Anumol; Jose, Densely; Joy, Sherin
• Is Part Of: ChemistrySelect. Volume 7:Issue 48(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-21
• Subjects: Charge transfer -- DFT -- Donor-Acceptor molecules -- Hole migration -- Regioisomers -- Spiro compounds; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202203188
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: The electronic structure, stereochemical aspects and charge transfer properties of the spiro compound (5S, 8S) spiro‐{6‐phenyl‐1‐aza‐3‐oxa‐7‐thia‐bicyclo[3, 3, 0]‐octene‐8, 3'(2'H)‐indol}‐2'‐one (spiro bicyclo adduct) synthesized using the multi‐component reaction via 1, 3‐dipolar cycloaddition of isatin and thioproline with the dipolarophile phenylacetylene have been studied. The two lowest energy regio‐isomers of the spiro heterocycle formed from the stereospecific dipolar reaction have been analysed along with the electron‐withdrawing and releasing substituents using DFT method at the CAM‐B3LYP/6‐311++G(d, p) level of theory. The atomic charges and the stabilization energy due to the intramolecular charge delocalization process calculated using the natural orbitals at the different molecular sites reveal the different donor‐acceptor interactions occurring in the system. The intramolecular electronic transitions (specifically n to π* and π to π*) is found to occur from the localized donor end component to the acceptor end components in the multi‐component system. The hole produced by the ionization of the entities is found to migrate from the thioproline component to the phenyl acetylene part in a time scale of around 4 fs. The electron‐withdrawing and donating substituents on the spirobicyclo adduct have been proven to tune the excited and ground state charge transfer properties uniquely. The results can shed light on how multi‐component reactions can be directed to produce spiro adducts with versatile applications. Abstract : The effect of regioisomerism and substituents on the ground and excited state charge transfer properties of a spiro bicyclic adduct is presented. Intramolecular charge transfer after excitation studied using TDDFT is found to be from the thioproline end to the isatin component. The hole created after ionization of the entity is found to evolve over time and migrates from thioproline to isatin unit in femtosecond timescale.