Table 1 Triplet energies and redox potentials of photocatalystsa.

From: Alkyne–Alkene [2 + 2] cycloaddition based on visible light photocatalysis

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Entry

Photocatalyst

E1/2(M*/M+)/E1/2(M*/M−) (V vs SCE)

ET (kcal/mol)

Yieldb

1c

PC I

−0.89/+1.21

60.8

83%

2d

PC I

−0.89/+1.21

60.8

75%

3

PC II

−1.23/+1.40

60.5

74%

4

PC III

−0.97/+0.97

60.4

74%

5

PC IV

−0.93/+1.14

55.4

62%

6

PC V

−1.04/+1.07

53.0

35%

7

PC VI

−0.96/+0.66

49.2

trace

8

Ru(bpy)3(PF6)2

−0.81/+0.77

46.5

n.r.

9e

Eosin Y

−1.11/+0.83

43.6

n.r.

  1. aReactions were performed with 0.05 mmol scale under Ar. Racemate for 3aa. p-Tol = p-tolyl, bpy = 2,2′-bipyridine, n.r. = no reaction.
  2. bYields determined by 1H NMR spectroscopic analysis against an internal standard. (1,1,2-trichloroethene).
  3. cReaction was performed with 1.5 equiv. of 2a and 2.5 mol% of PC I in CH2Cl2 (0.05 M).
  4. dReaction was performed with 1.5 equiv. of 2a and 1.0 mol% of PC I in CH2Cl2 (0.05 M).
  5. eGreen LED instead of blue LED.
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