# Microanalytical data C H and N were

Table 2.

Fig. 4. HOMO and LUMO molecular orbitals of ligand (HL).Figure optionsDownload full-size imageDownload as PowerPoint slide

Table 3.

The calculated quantum chemical parameters of Sulfo-NHS-SS-Biotin ligand (HL).ParameterEHOMO (a.u.)− 0.19739ELUMO (a.u.)− 0.06899μ (D)4.529T.E (a.u)− 1082.473ΔE (a.u.)0.1284χ (a.u.)0.1331η (a.u.)0.0642σ (a.u.)− 115.578Pi (a.u.)− 0.1331S (a.u.)− 17.7888ω (a.u.)0.1379?Nmax2.074Full-size tableTable optionsView in workspaceDownload as CSV

The HOMO–LUMO energy gap, ΔE, which is an important stability index, is applied to develop theoretical models for explaining the structure and conformation barriers in many molecular systems. Recently, the energy gap has been used to prove the reactivity and stability of the compounds [3] and [12]. The dipole moment, μ, the first derivative of the energy with respect to an applied electric field, was used to discuss and rationalize the structure [3] and [12].