Donor–acceptor preassociation, excited state solvation threshold, and optical energy cost as challenges in chemical applications of photobases

Abstract

Photobases convert light energy to proton removal power. What limits their applicability? Hydrogen bonding, solvation, and photon energy cost.

Photoinduced Proton‐Transfer Reactions for Mild O‐H Functionalization of Unreactive Alcohols

“…Excited‐state reactivity has developed into a fundamental reaction principle over the past few years and is today an indispensable tool to conduct organic synthesis by facilitating elementary reactions steps, for example, photoinduced electron‐ or proton‐transfer reactions . With the resurgence of photoredox catalysis over the past decade, photoinduced electron‐transfer reactions have found their way into the standard repertoire of organic chemistry .…”

Structure–Photochemical Function Relationships in Nitrogen-Containing Heterocyclic Aromatic Photobases Derived from Quinoline

“…[12][13][14][15][16][17][18][19] Recent experimental studies performed in the Dawlaty lab have investigated the photochemical properties of a family of 5-R quinoline derivatives. [20][21][22][23][24][25] These compounds were all shown to be photobases, with the magnitude of the photobasicity depending strongly on the identity of the substituent. Specifically, photoexcitation results in Kb increasing by over 10 orders of magnitude when the substituent is the electron-donating NH2 group but only approximately 2 orders of magnitude when the substituent is the electron-withdrawing CN group.…”

“…Collectively, this work further refines the design principles necessary to develop new photocatalysts which employ photobasicity. Figure 1 illustrates the Förster cycle used to calculate DG* and hence p # * from a series of quantities that are readily obtained from electronic structure calculations, specifically ∆ * = ∆ + ∆ 11 2 − ∆ 11 24 . In this equation, the ground state DG is related to DG* through the adiabatic SCT-S0 energy gaps of the base and conjugate acid, ∆ 11 2 and ∆ 11 24 .…”

Structure-Photochemical Function Relationships in Nitrogen-Containing Heterocyclic Aromatic Photobases Derived from Quinoline

“…[12][13][14][15][16][17][18][19] Recent experimental studies performed in the Dawlaty lab have investigated the photochemical properties of a family of 5-R quinoline derivatives. [20][21][22][23][24][25] These compounds were all shown to be photobases, with the magnitude of the photobasicity depending strongly on the identity of the substituent. Specifically, photoexcitation results in Kb increasing by over 10 orders of magnitude when the substituent is the electron-donating NH2 group but only approximately 2 orders of magnitude when the substituent is the electron-withdrawing CN group.…”

“…Figure 1 illustrates the Förster cycle used to calculate DG* and hence p # * from a series of quantities that are readily obtained from electronic structure calculations, specifically ∆ * = ∆ + ∆ 11 2 − ∆ 11 24 . In this equation, the ground state DG is related to DG* through the adiabatic SCT-S0 energy gaps of the base and conjugate acid, ∆ 11 2 and ∆ 11 24 . More specifically, ∆ 11 2 = 5 67 8 − 5 9 8 , where 5 67 8 is the electronic energy of the charge-transfer SCT state at the SCT minimum energy geometry while 5 9 8 is the S0 electronic energy at the S0 minimum energy geometry.…”