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. 2016 Jul 6;1(1):66-76.
doi: 10.1021/acsomega.6b00058. eCollection 2016 Jul 31.

Library of Cationic Organic Dyes for Visible-Light-Driven Photoredox Transformations

Spencer P Pitre  1 , Christopher D McTiernan  1 , Juan C Scaiano  1
Affiliations

Library of Cationic Organic Dyes for Visible-Light-Driven Photoredox Transformations

Spencer P Pitre et al. ACS Omega. .

Abstract

Organic dyes can be excellent catalysts for photoredox chemistry, offering low price, low toxicity, and an exceptional range of available materials. Their use has been limited because in comparison to their transition-metal catalysts the spectroscopic, kinetic, and electrochemical information available is far more limited. To remediate this situation, we have determined the necessary data for 14 readily available dyes with excellent potential as photoredox catalysts. We have also demonstrated the utility of these dyes through visible-light-mediated reductive dehalogenation and Aza-Henry reactions. We envision that this collection of data will lead to an increase in the use of cationic dyes in photoredox processes because users will find the necessary information readily available.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Basic structural representation of the organic dyes investigated in this work and a typical photoredox cycle.
Scheme 1
Scheme 1. Proposed Catalytic Cycle and Chain Reaction for the Reductive Dehalogenation of meso-1,2-Dibromo-1,2-diphenylethane Using Cationic Organic Photosensitizers
Scheme 2
Scheme 2. (A) Reductive Dehalogenation Experiments Employing Ru(bpy)3Cl2 and fac-Ir(ppy)3 as the Photosensitizer and (B) Bimolecular Quenching Constants for the Ru(bpy)3Cl2-Catalyzed Reaction
Scheme 3
Scheme 3. Proposed Mechanism for the Visible-Light-Mediated Aza-Henry Reaction
Note that reactions of 1O2 are viable only for examples in which triplet-state dyes are employed.
Figure 2
Figure 2
Plot of percent yield of the Aza-Henry product versus the percent of *dye quenched by PhTHIQ for all cationic dyes examined in this study. Dye legend: thiazine (blue •), oxazine (red ◊), xanthene (Δ), and azine (green ■).
Figure 3
Figure 3
Plot of percent yield of the Aza-Henry product versus the Gibbs’ free energy for photoinduced electron transfer (ΔGeT) for all cationic dyes examined in this study. Dye legend: thiazine (blue •), oxazine (red ◊), xanthene (Δ), and azine (green ■).
See this image and copyright information in PMC

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