Table 1. UV–Vis Data for I–II and 1–10 in (THF/DMSO).

compound	anionic unit in complex	P=O unit of Ln	visible-light absorption region (nm)	λmax (nm)	ε (M–1 cm–1)
I	CA	R2R′PO of L1	360–700	500	9824
1	DHBQ	R2R′PO of L1	350–700	488	10 387
2	CA	R2R′PO of L2	350–700	496	11 620
5	DHBQ	R2R′PO of L2	350–700	482	5610
3	CA	R2R′PO of L3	365–710	497	4130
6	DHBQ	R2R′PO of L3	350–700	480	4146
4	CA	(R′′O)2R′PO of L4	350–710	495	11 170
7	DHBQ	(R′′O)2R′PO of L4	350–680	472	18 324
II	CA	(R′′O)2R′PO of L5	360–700	500	14 768
8	DHBQ	(R′′O)2R′PO of L5	340–700	472	26 796
9	thq	R2R′PO of L2	400–600	450	6788
10	thq	R2R′PO of L3	370–600	391	7972

^aR = phenyl, R′ = CH₂, and R′′ = CH₃.