Photochemistry

Photochemistry uses absorbed light to generate excited states, radicals or catalytic redox cycles that thermal reactions cannot reach at the same temperature.

Visible-light photoredox is now core undergraduate organic chemistry, and chain vs closed-cycle behaviour changes how you count photons.

Claim ledger

What the evidence shows

Drawn from 10 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.

• ● Supporting studies only

  This library holds 10 empirical chemistry papers on photochemistry with isolated findings, rates or spectra rather than reviews.

  3 studies
  1. 1DASA photoswitches work in chloroform if N-methyl
  2. 2Platinum photoredox catalysts for trifluoromethylation
  3. 3Strongly reducing Ir photoredox on aryl chlorides

  Study comparison

  Study	Role	Design	N	Population	Outcome
  DASA photoswitches work in chloroform if N-methyl2018	Supports	OtherSynthesis and photoswitching kinetics/fatigue of DASA photochromes 1–14	Molecular photochrome SAR — no sample N	Donor–acceptor Stenhouse adduct photoswitches	Photoswitching amplitude, kinetics, and fatigue related to substituents
  Platinum photoredox catalysts for trifluoromethylation2015	Supports	OtherBlue-LED photoredox trifluoromethylation catalyzed by cyclometalated Pt(II) complexes	Synthetic photoredox catalysis — no sample N	Alkenes and heteroarenes under Pt(II)/CF3I photoredox conditions	Trifluoromethylation yields and oxidative-quenching mechanism
  Strongly reducing Ir photoredox on aryl chlorides2021	Supports	Animal / in-vitroIr(ppy)2(NacNac) photoredox hydrodehalogenation with BIH under blue or green LEDs	Substrate-scope reactions plus Stern–Volmer and quantum-yield measurements	Unactivated aryl bromides, chlorides, fluorides, and alkyl bromides	Strongly reducing iridium photosensitizers hydrodehalogenate unactivated substrates, including under green light

• ○ Limited citations

  First-generation donor–acceptor Stenhouse adducts with a small N-methyl substituent switch well in chloroform; kinetics split photoisomerisation from cyclisation.

  1 study
  1. 1DASA photoswitches work in chloroform if N-methyl

• ○ Limited citations

  Cyclometalated Pt(II) complexes trifluoromethylate unactivated alkenes in >82% yield under 450 nm LEDs by oxidatively quenching CF3I.

  1 study
  1. 1Platinum photoredox catalysts for trifluoromethylation

• ○ Limited citations

  Ir(ppy)2(NacNac) photocatalysts with BIH hydrodehalogenate unactivated aryl bromides, chlorides, fluorides, and alkyl bromides, including with green light.

  1 study
  1. 1Strongly reducing Ir photoredox on aryl chlorides

• ○ Limited citations

  A visible-absorbing Eu(II) azacryptate, assembled in situ from EuCl3, ligand and Zn0, reductively couples benzyl chloride to 1,2-diphenylethane with an excited-state potential near −3 V.

  1 study
  1. 1Eu(II) cryptate photocatalyzes bibenzyl coupling

Debates

Tensions and limits

Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.

Timeline

How understanding moved

Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.

Papers

10 studies in this library bear on Photochemistry, ordered by citations.

• Photoredox reactions that run as radical chains

  Quantum yields of 44, 77, and 18 show product-forming chains—not a closed photocatalytic cycle of Φ ≤ 1—in three visible-light reactions.

  Chemical science · 2015 · 617 citations

• PQ and water oxy-trifluoromethylate enynes

  Sunlight-excited phenanthrenequinone turns Langlois’ CF3SO2Na into CF3· and uses water as the oxygen atom to build CF3 benzofurans, benzothiophenes and indoles.

  Chemical science · 2017 · 71 citations

• Platinum photoredox catalysts for trifluoromethylation

  Cyclometalated Pt(II) complexes trifluoromethylate unactivated alkenes in >82% yield under 450 nm LEDs by oxidatively quenching CF3I.

  Chemical science · 2015 · 70 citations

• DASA photoswitches work in chloroform if N-methyl

  First-generation donor–acceptor Stenhouse adducts with a small N-methyl substituent switch well in chloroform; kinetics split photoisomerisation from cyclisation.

  Chemical science · 2018 · 69 citations

• Strongly reducing Ir photoredox on aryl chlorides

  Ir(ppy)2(NacNac) photocatalysts with BIH hydrodehalogenate unactivated aryl bromides, chlorides, fluorides, and alkyl bromides, including with green light.

  Chemical science · 2021 · 58 citations

• Green-light ATRP that tolerates open air

  Eosin Y plus a copper ATRP catalyst polymerizes OEOMA under green light in open vials, giving low dispersity even at 1000 rpm stirring.

  Chemical science · 2022 · 56 citations

• Eu(II) cryptate photocatalyzes bibenzyl coupling

  A visible-absorbing Eu(II) azacryptate, assembled in situ from EuCl3, ligand and Zn0, reductively couples benzyl chloride to 1,2-diphenylethane with an excited-state potential near −3 V.

  Chemical science · 2018 · 52 citations

• ML and high-throughput screens find organic H2 photocatalysts

  Screening 572 then 96 organic molecules under identical HER conditions, plus ML, uncovered unexpected molecular photocatalysts rivaling conjugated polymers.

  Chemical science · 2021 · 48 citations

Questions

What is still open

1. Quantum yield, wavelength and quencher identity vary widely; a 'photocatalyst' can be a chain initiator rather than a closed cycle.

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