Table 1.

Frontier orbital energy levels and optical bandgaps of B←N embedded π-units.

Compounds	HOMO (eV)	LUMO (eV)	$E_g^{opt}$ (eV)b
20	−5.66	−3.44	–
21	−5.72	−4.40	1.59
22	−5.54	−3.68	–
23	−5.40	−4.21	1.34
78	−6.00	−3.73	2.29
79	−5.96	−4.15	1.73
80	−6.27	−3.52	2.59
81	−6.19	−4.11	1.92
82	−6.34	−3.52	2.82
83	−6.11	−4.11	2.02
84	−5.52a	−1.78a	3.58
85	−6.68a	−2.88a	3.52
7	−6.36a	−3.01a	3.11
86	−5.38a	−2.21a	3.25
87	−6.55a	−3.34a	3.19
8	−6.17a	−3.30a	2.87
88	−4.54a	−1.81a	–
89	−4.76a	−2.44a	–

^aObtained by theoretical calculations. Other HOMOs and LUMOs were estimated by electrochemistry method.

^bCalculated by 1240/λ_onset. λ_onset is the absorption onset of UV-Vis absorption spectra.