Palladium-catalyzed synthesis of pyrimidine substituted diaryl ethers through Suzuki Miyaura coupling reactions: Experimental and DFT studies

Aryl and hetero-aryl substituted pyrimidine derivatives demonstrate widespread applications in nonlinear optics (NLO), agrochemical and therapeutic drugs. Therefore, 2-(4-phenoxyphenyl) pyrimidine (2-PPP) and 5-(4-phenoxyphenyl) pyrimidine (5-PPP) were synthesized by palladium-catalyzed Suzuki coupling approach. The structure elucidation of synthesized products was done by H-1-NMR, C-13-NMR, and UV-vis spectroscopic analyses. The natural bond orbital (NBO) analysis was performed using density functional theory (DFT) assisted M06/6-311G** functional, which confirmed the existence of delocalization process and the hyper-conjugative interaction with representative transitions as pi(C10-N16)->pi*(C14-N17) and pi(C26-N30)->pi* (C9-N31) having stabilization energies of 36.30 and 36.55 kcal/mol for 2-PPP and 5-PPP, respectively. The small energy Delta E (LUMO HOMO) gap as 5.330 eV in 2-PPP and 4.975 eV in 5-PPP was evident from the frontier molecular orbital (FMO) analysis, computed at TD-DFT/M06/6-311G** level, Both the NBO and the FMO analysis predicted promising NLO molecular response. Furthermore, HF, LC-BLYP, CAM-B3LYP, M06-2X, and M06 methods, along with the 6-311G** basis set, were utilized to acquire the NLO findings of 2-PPP and 5-PPP. M06 and HF methods indicated the largest and lowest values of average polarizability <alpha > and first hyperpolarizability (beta(tot)), respectively for both the compounds 2-PPP and 5-PPP. The <alpha > and beta(tot) values of 2-PPP and 5-PPP were observed respectively. Both compounds hold fine NLO characteristics, thus recommended for future NLO applications.