Table 7.

Quantum chemical properties of DPP-4–ligand complexes.

Properties (eV)	S1	T1	T4	T2
HOMO	−0.20306	−0.24354	−0.24676	−0.24692
LUMO	0.06017	0.04816	0.05232	0.05377
Band gap	0.26323	0.2917	0.29908	0.30069
Electronegativity	0.071445	0.09769	0.09722	0.096575
Ionization potential	0.20306	0.24354	0.24676	0.24692
Electron affinity	−0.06017	−0.04816	−0.05232	−0.05377
Hardness	0.131615	0.14585	0.14954	0.150345
softness	3.798959	3.42818	3.343587	3.325684
Chemical potential	−0.07145	−0.09769	−0.09722	−0.09658
Electrophilicity	0.002552	0.004772	0.004726	0.004663