Quantum chemical analysis of reactivity of several chromenopyrazoles

Abstract

The article presents the results of quantum chemical calculation of reactivity indices of nine substituted chromenopyrazoles that can be potentially used as ligands for light emitting complex compounds. The molecules chosen for our study contain several potential complexation centers (nitrogen atoms of pyrazol ring and oxygen atoms of chromene fragment) as well as additional chromophoric groups capable of facilitating the excitation energy transfer from ligand to central ion. The molecular geometry was optimized using Hartree-Fock method and 6-311 G basis set implemented in Firefvly v. 8.1.0 software package. According to calculation results, the most probable center of nucleophilic attack is C 7 carbon atom of chromene fragment, while the most probable centers of electrophilic attack are C3 carbon atom of chromene fragment and C27 carbon atom of carbamid group. Addition of bromine and hydroxyl groups to chromene fragment as well as carbamid or thioamid group to pyrazol ring decresased the electron donor properties and increased the electorn acceptor properties of studied molecules. 5-hydroxy-3-(5-methyl-5-H-pyrazol-3-yl)-2H-chromene-2-one is the best electron acceptor while 3-(5-methyl-5H-pyrazol3-yl)-2H-chromene-2-one is the best electron donor. The best candidate among studied compounds for electron-donor substances that can be used as a basis for effi cient organic light-emitting diode is 3-(5-methyl-5H-pyrazol-3-yl)-2H-chromene-2-one.

Keywords

• chromenepyrazoles
• ab initio calculations
• reactivity indices
• electron donor properties