Search results
Search for "NIR light" in Full Text gives 11 result(s) in Beilstein Journal of Organic Chemistry.
Photoswitches beyond azobenzene: a beginner’s guide
- Michela Marcon,
- Christoph Haag and
- Burkhard König
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Research progress on calixarene/pillararene-based controlled drug release systems
- Liu-Huan Yi,
- Jian Qin,
- Si-Ran Lu,
- Liu-Pan Yang,
- Li-Li Wang and
- Huan Yao
Beilstein J. Org. Chem. 2025, 21, 1757–1785, doi:10.3762/bjoc.21.139
- the anticancer drug DOX. Both the acidic microenvironment at the tumor site and photothermal effects can induce the release of DOX. DOX delivered by these vesicles, in combination with NIR light irradiation, can significantly suppress tumor growth. Wang and colleagues [107] designed a supramolecular
Graphical Abstract
Figure 1: Schematic diagram of drug-controlled release mechanisms based on aromatic macrocycles.
Figure 2: Chemical structure of a) calix[n]arene (m = 1,3,5), and b) pillar[n]arene (m = 1,2,3).
Figure 3: Changes in pH conditions cause the release of drugs from CA8 host–guest complexes [101]. Figure 3 was adapted wi...
Figure 4: The illustration of the pH-mediated 1:1 complex formation between the host and guest molecules in a...
Figure 5: Illustration of the pH-responsive self-assembly of mannose-modified CA4 into micelles and the subse...
Figure 6: Illustration of the assembly of supramolecular prodrug nanoparticles from WP6 and DOX-derived prodr...
Figure 7: Illustration of the formation of supramolecular vesicles and their pH-dependent drug release [93]. Figure 7 was...
Figure 8: Schematic illustration of the application of the multifunctional nanoplatform CyCA@POPD in combined...
Figure 9: Illustration of the photolysis of an amphiphilic assembly via CA-induced aggregation [114]. Figure 9 was reprint...
Figure 10: Schematic illustration of drug release controlled by the photo-responsive macroscopic switch based ...
Figure 11: Schematic illustration of the formation process of Azo-SMX and its photoisomerization reaction unde...
Figure 12: Schematic illustration of the enzyme-responsive behavior of supramolecular polymers [95]. Figure 12 was used wit...
Figure 13: Schematic illustration of the amphiphilic assembly of SC4A and its enzyme-responsive applications [119]. ...
Figure 14: Stimuli-responsive nanovalves based on MSNs and choline-SC4A[2]pseudorotaxanes, MSN-C1 with ester-l...
Figure 15: A schematic diagram showing the construction of a supramolecular system by host–guest interaction b...
Figure 16: A schematic diagram showing the formation of the host–guest complex DOX@Biotin-SAC4A by biotin modi...
Figure 17: A schematic diagram showing the self-assembly of CA4 into a hypoxia-responsive peptide hydrogel, wh...
Figure 18: Schematic illustration of the formation process of Lip@GluAC4A and the release of Lip under hypoxic...
Figure 19: Schematic illustration of the construction of a supramolecular vesicle based on the host–guest comp...
Figure 20: Schematic illustration of WP6 self-assembly at pH > 7, and the stimulus-responsive drug release beh...
Figure 21: Schematic illustration of the formation of supramolecular vesicles based on the WP5⊃G super-amphiph...
Figure 22: Schematic illustrations of the host–guest recognition of QAP5⊃SXD, the formation of the nanoparticl...
Figure 23: Schematic illustration of the activation of T-SRNs by acid, alkali, or Zn2+ stimuli to regulate the...
Figure 24: Illustration of the triggered release of BH from CP[5]A@MSNs-Q NPs in response to a drop in pH or a...
Figure 25: Illustration of the supramolecular amphiphiles TPENCn@1 (n = 6 and 12) self-assembling with disulfi...
Red light excitation: illuminating photocatalysis in a new spectrum
- Lucas Fortier,
- Corentin Lefebvre and
- Norbert Hoffmann
Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22
- 40 has been proven to be the most efficient photocatalyst, promoting key transformations such as the aza-Henry reaction with 44 to give 45 under NIR light irradiation (Figure 6b). The reaction was found to critically depend on the presence of oxygen in the air for it to proceed. Through optimization
- novel approach to harnessing NIR light for challenging chemical transformations. The helical carbenium ion, dimethoxyquinacridinium (DMQA+) and its synthesis, has been extensively studied for its photophysics, making it a subject of significant interest in the field of photocatalysis [67][68]. Based on
- reactions are of high interest for being applied in biological or medicinal domains. However, the weak light penetration of biological tissues limits the application to surface processes. The penetration of NIR light is considerably better [71]. Consequently, many photochemical processes are currently
Graphical Abstract
Figure 1: Influence of the metal center M (Fe, Ru, Os) on the position of the MLCT and MC (metal-centered) ab...
Scheme 1: Red-light-mediated ring-closing metathesis through activation of a ruthenium catalyst by an osmium ...
Scheme 2: Photocatalyzed polymerization of dicylopentadiene mediated with red or blue light.
Figure 2: Comparison between [Ru(bpy)3]2+ and [Os(tpy)2]2+ in a photocatalyzed trifluoromethylation reaction:...
Scheme 3: Red-light photocatalyzed C–N cross-coupling reaction by T. Rovis et al. (SET = single-electron tran...
Figure 3: Red-light-mediated aryl oxidative addition with a bismuthinidene complex.
Scheme 4: Red-light-mediated reduction of aryl derivatives by O. S. Wenger et al. (PC = photocatalyst, anh = ...
Scheme 5: Red-light-mediated aryl halides reduction with an isoelectronic chromium complex (TDAE = tetrakis(d...
Scheme 6: Red-light-photocatalyzed trifluoromethylation of styrene derivatives with Umemoto’s reagent and a p...
Scheme 7: Red-light-mediated energy transfer for the cross-dehydrogenative coupling of N-phenyltetrahydroisoq...
Scheme 8: Red-light-mediated oxidative cyanation of tertiary amines with a phthalocyanin zinc complex.
Scheme 9: Formation of dialins and tetralins via a red-light-photocatalyzed reductive decarboxylation mediate...
Scheme 10: Oxidation of β-citronellol (28) via energy transfer mediated by a red-light activable silicon phtha...
Scheme 11: Formation of alcohol derivatives 32 from boron compounds 31 using chlorophyll (chl) as a red-light-...
Scheme 12: Red-light-driven reductive dehalogenation of α-halo ketones mediated by a thiaporphyrin photocataly...
Figure 4: Photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization medi...
Figure 5: Recent examples of red-light-mediated photocatalytic reactions with traditional organic dyes.
Figure 6: Squaraine photocatalysts used by Goddard et al. and aza-Henry reaction with squaraine-based photoca...
Figure 7: Reactions described by Goddard et al. involving 40 as the photocatalyst.
Figure 8: Various structures of squaraine derivatives used to initiate photopolymerizations.
Figure 9: Naturally occurring cyanins.
Figure 10: Influence of the structure on the photophysical properties of a cyanin dye.
Figure 11: NIR-light-mediated aza-Henry reaction photocatalyzed by 46.
Scheme 13: Photocatalyzed arylboronic acids oxidation by 46.
Figure 12: Cyanin structures synthetized and characterized by Goddard et al. (redox potentials given against s...
Figure 13: N,N′-Di-n-propyl-1,13-dimethoxyquinacridinium (55) with its redox potentials at its ground state an...
Scheme 14: Dual catalyzed C(sp2)–H arylation of 57 using DMQA 55 as the red-light-absorbing photocatalyst.
Scheme 15: Red-light-mediated aerobic oxidation of arylboronic acids 59 into phenols 60 via the use of DMQA as...
Figure 14: Red-light-photocatalyzed reactions proposed by Gianetti et al. using DMQA as the photocatalyst.
Scheme 16: Simultaneous release of NO and production of superoxide (O2•−) and their combination yielding the p...
Figure 15: Palladium porphyrin complex as the photoredox catalyst and the NO releasing substrate are linked in...
Scheme 17: Uncaging of compound 69 which is a microtubule depolymerizing agent using near IR irradiation. The ...
Scheme 18: Photochemical uncaging of drugs protected with a phenylboronic acid derivative using near IR irradi...
Scheme 19: Photoredox catalytical generation of aminyl radicals with near IR irradiation for the transfer of b...
Scheme 20: Photoredox catalytical fluoroalkylation of tryptophan moieties.
Figure 16: Simultaneous absorption of two photons of infrared light of low energy enables electronic excitatio...
Scheme 21: Uncaging Ca2+ ions using two-photon excitation with near infrared light.
Photochromic derivatives of indigo: historical overview of development, challenges and applications
- Gökhan Kaplan,
- Zeynel Seferoğlu and
- Daria V. Berdnikova
Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23
- new level of complexity and promise. The photochromic indigos represent a relatively rare type of visible-light-responsive T-type photoswitches demonstrating negative photochromism. The absorption of the photoswitchable indigos covers the spectral range from green to NIR light (≈550–700 nm) making
Graphical Abstract
Figure 1: Precursors used in the synthesis of indigo [4].
Figure 2: a) Intramolecular (a = 2.26 Å) and intermolecular (b = 2.11 Å) hydrogen bonds in indigo, b) crystal...
Figure 3: Bond length in the indigo molecule obtained from the single crystal X-ray analysis [12], the typical bo...
Figure 4: The structure of the indigo chromophore (H-chromophore, highlighted in blue), asterisk indicates th...
Figure 5: Influence of substituents in the benzene rings on the color of indigo derivatives.
Figure 6: a) E–Z photoisomerization of indigo and b) photoinduced proton transfer in the excited state, aster...
Figure 7: Structures of indigo derivatives discussed in this review.
Figure 8: Photoswitching of N,N'-diacetylindigo (9a) in CCl4 (c = 17.1 µM; cell length = 5.0 cm) irradiated w...
Figure 9: Photoisomerization of compound 18c upon irradiation with red light and schematic representation of ...
Figure 10: Schematic representation of indigo-type (left) and amide-type (right) resonances in N,N'-acetylindi...
Figure 11: Suggested intermediates for the double bond cleavage for the thermal relaxation of N,N'-diacylindig...
Figure 12: Zwitterionic resonance structures of Z-indigo.
Figure 13: Photos of crystalline N,N'-di(Boc)indigo 17a its solutions in 1) DMSO, 2) DMF, 3) N-methyl-2-pyrrol...
Figure 14: Structural isomers of indigo.
Figure 15: Photochromism of indirubin derivatives and supramolecular complexation of the E-isomers with Schrei...
Figure 16: Photoisomerization of the protonated isoindigo.
Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation
- Azra Kocaarslan,
- Zafer Eroglu,
- Önder Metin and
- Yusuf Yagci
Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164
- , we present a novel synthetic methodology for the photoinduced CuAAC reaction utilizing exfoliated two-dimensional (2D) few-layer black phosphorus nanosheets (BPNs) as photocatalysts under white LED and near-IR (NIR) light irradiation. Upon irradiation, BPNs generated excited electrons and holes on
- azide derivatives under both white LED and NIR light irradiation. Due to its deeper penetration of NIR light, the possibility of synthesizing different macromolecular structures such as functional polymers, cross-linked networks and block copolymer has also been demonstrated. The structural and
- . In this work, we report a new synthetic strategy to the photochemical reduction of CuII to CuI for the CuAAC reaction using BPNs as the photo-initiator under NIR light. Results and Discussion The detailed preparation and characterization of the initial BP crystals and BPNs were previously reported
Graphical Abstract
Figure 1: Structures of azide and alkyne functional molecules and polymers used in the photoinduced CuAAC rea...
Figure 2: UV–vis spectra of CuICl, CuIICl2 and BPNs.
Figure 3: a) 1H NMR spectra of the model reaction between benzyl azide (Az-1) and phenylacetylene (Alk-3) bef...
Scheme 1: Proposed mechanism for photoinduced CuAAC reaction using exfoliated BPNs.
Figure 4: a) 1H NMR spectrum of chain end modified PCL-Anth; b) UV–vis spectra of (azidomethyl)anthracene (bl...
Scheme 2: Synthesis of PS-b-PCL block copolymer via exfoliated BPNs-mediated photoinduced CuAAC reaction.
Figure 5: a) GPC traces of PS-Az, PCL-Alk and block copolymer (Ps-b-PCL) b) 1H NMR spectrum of the block copo...
Scheme 3: Preparation of the cross-linked polymer by CuAAC reaction using multifunctional monomers, Az-3 and ...
Figure 6: a) DSC thermogram of photoinduced synthesis of nanocomposite networks (heating rate: 10 °C/min). b)...
Figure 7: (a, b) TEM images of cross-linked polymer at two different magnifications, c) HAADF-STEM image and ...
Towards new NIR dyes for free radical photopolymerization processes
- Haifaa Mokbel,
- Guillaume Noirbent,
- Didier Gigmes,
- Frédéric Dumur and
- Jacques Lalevée
Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133
- and safe near-infrared (NIR) light is still the subject of intense research efforts but remains a huge challenge due to the associated low photon energy (wavelength from 0.78 to 2.5 µm). In this study, a series of 17 NIR dyes mainly based on a well-established cyanine scaffold is proposed. Remarkably
- , 11 of them were never synthesized before. Markedly, noncharged structures, negatively charged cyanine bearing Na+ as counter cation, and positively charged cyanines bearing (B(Ph)4−) or (I−) as counter anions were examined as promising NIR light photoinitiating systems. Excellent photoinitiating
- polymerization of acrylate/epoxy monomer blends) can also be carried out upon NIR light with the proposed systems. Keywords: cyanine; NIR light; photochemistry; Introduction Photopolymerization processes are well established due to the specific features and advantages. Indeed, the reaction is carried out at
Graphical Abstract
Scheme 1: Investigated NIR dyes.
Scheme 2: Other used chemicals.
Scheme 3: Synthetic routes to compounds Ca, Cb, and CNa.
Scheme 4: Synthetic routes to CI1, CI3, CI4, and CI6–CI9.
Scheme 5: The metathesis reaction enabling the formation of “soft” salts CBPh1-CBPh4.
Figure 1: Visible–NIR spectra of NIR dyes in ACN. A) (1) CBPh1, (2) CBPh2, (3) CBPh3, (4) CBPh4, (5) Ca, (6) ...
Figure 2: Photopolymerization profiles of PETIA monomer under air (acrylate functions conversion vs irradiati...
Figure 3: Photopolymerization profiles of PETIA monomer under air (acrylate functions conversion vs irradiati...
Scheme 6: Pictures of polymers obtained for a thickness of 1.4 mm, using a NIR dye/iod/amine 0.1:3:2, %w/w/w ...
Scheme 7: Proposed mechanism for the photochemical reactivity of NIR dyes in a three-component PIS.
Figure 4: A) Photopolymerization profiles of PETIA/epoxy blend 1:1, w/w under air (acrylate and epoxy functio...
Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0
- Bernd Strehmel,
- Christian Schmitz,
- Ceren Kütahya,
- Yulian Pang,
- Anke Drewitz and
- Heinz Mustroph
Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40
- applications related to Chemistry 4.0 standards. These were mainly photopolymer coatings, which can be found for applications in the graphic industry or to protect selected substrates. The huge release of heat on demand upon turning ON or OFF the NIR light source enables them for photothermal treatment in
- polymerization (NMP) processes, reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP) [118]. While there has been no report available with NIR-sensitized NMP, there exist a few reports for RAFT polymerization with NIR light [119][120][121]. Recently, ATRP with Cu
- , zwitterionic and anionic patterns shown in Scheme 10. The polymers obtained exhibited quite high molecular weights (more than 2 × 105 g·mol−1) and failed to exhibit living character [81]. However, this system exhibited a successful route with Cu(II) catalysts at the ppm scale [81]. Quite recently, NIR light
Graphical Abstract
Scheme 1: Structural patterns of several symmetric cyanines relating to trimethines (I), pentamethines (II), ...
Scheme 2: 1-Substituted 2,3,3-trimethylindolium-, 2,3,3-benzo[e]indolium-, and 2,3,3-benzo[c,d]indolium salts...
Scheme 3: Substitution of the chlorine substituent at the meso-position by a stronger nucleophilic moiety B [68].
Scheme 4: Structure of alternative chain builders for synthesis of heptamethines.
Figure 1: Simplified process chart of photophysical processes occurring in NIR absorbers.
Scheme 5: Chemical structure of the electron acceptors that were from iodonium cations 88 and triazines 89.
Figure 2: Photoinduced electron transfer under different scenarios in which each example exhibits an intrinsi...
Scheme 6: Photoexcited absorber 33 results in reaction with an iodonium cation in the respective cation radic...
Scheme 7: Reaction scheme of absorbers comprising in the molecules center a five ring bridged moiety. This le...
Scheme 8: Structure of donor compounds used in a three component system.
Figure 3: Cationic photopolymerization of an epoxide (Epikote 828) initiated by excitation of the absorber 36...
Scheme 9: Different modes of photoinitiated ATRP using UV, visible and NIR light.
Scheme 10: The structure of Sens used in photo-ATRP.
Figure 4: Comparison of the GPC traces of precursor PMMA with a) chain extended PMMA and b) PMMA-b-PS. Condit...
Figure 5: Spectral changes of the solution of 48 in the presence of [Cu(L)]Br2 (L: tris(2-pyridylmethyl)amine...
Scheme 11: Photoinduced CuAAC reactions in which photochemical reactions result in formation of the Cu(I) cata...
Scheme 12: Model reaction between benzyl azide and phenyacetylene using the absorber 48 as NIR sensitizer at 7...
Figure 6: Block copolymerization of the precursors PS-N3 and Alkyne-PCL results in the block copolymer PS-b-P...
Figure 7: UV–vis–NIR absorption changes of the solution of 48 in the presence of PMDETA, phenylacetylene and ...
Scheme 13: Workflow to design and process new materials in a setup based on an intelligent DoE to develop tech...
Scheme 14: Illustration of the iDoE setting up experiments suggested and analyzed by the A.I. After defining t...
Scheme 15: Classification of the factors for the formation of polymer networks by NIR-photocuring depending on...
Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone
- Alessandro Iagatti,
- Baihao Shao,
- Alberto Credi,
- Barbara Ventura,
- Ivan Aprahamian and
- Mariangela Di Donato
Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236
- -photon excitation (i.e., near infrared (NIR) light), which is also maintained in serum and solid state, has a very high photochemical stability and excellent fatigue resistance. Although the main photochemical properties of this molecule have been recently reported [29], a detailed analysis of its
Graphical Abstract
Figure 1: a) The photoinduced Z/E isomerization of hydrazone 1, and accompanied changes in b) UV–vis absorpti...
Figure 2: Fluorescence decays (dots) in the 500–520 nm spectral region (emission range of the Z-isomer) for 1...
Figure 3: Fluorescence decays (dots) in the 500–520 nm spectral region (red; induced Z-emission), and in the ...
Figure 4: a) Transient absorption data recorded for hydrazone 1 in toluene upon excitation at 400 nm; b) EADS...
Figure 5: EADS obtained by global fit of the transient data recorded in a) acetonitrile and b) methanol upon ...
Figure 6: Kinetic traces recorded at the maximum of the excited state absorption band in toluene, acetonitril...
Figure 7: a) Transient absorption spectra measured for hydrazone 1 in toluene upon excitation at 785 nm. b) C...
Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes
- Andrey G. Lvov,
- Max Mörtel,
- Anton V. Yadykov,
- Frank W. Heinemann,
- Valerii Z. Shirinian and
- Marat M. Khusniyarov
Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235
- , which possess prominent luminescent and spectral properties, including photocyclization with visible and NIR light. Using the photochromic ligand I, a spin-crossover (SCO) Fe(II) complex was developed, which allowed a reversible paramagnetic (high-spin, S = 2) → diamagnetic (low-spin, S = 0) transition
Graphical Abstract
Figure 1: Families of diarylethene-bases ligands with spatial proximity of coordination site (blue) and photo...
Scheme 1: Synthesis of photochromic ligands.
Figure 2: Electronic spectra of diarylethene 6 upon UV irradiation (313 nm, toluene, c = 3.4 × 10−5 M). Inset...
Scheme 2: Reversible photocyclization of ligand 6.
Figure 3: Molecular structure of complexes 8 (top) and 9 (bottom) at 100 K. The H atoms are omitted for clari...
Figure 4: Variable temperature χT product (blue) and χ (green) of 8 (top) and 9 (bottom) measured at an exter...
Naphthalene diimides with improved solubility for visible light photoredox catalysis
- Barbara Reiß and
- Hans-Achim Wagenknecht
Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201
- fluorescence quantum yields are rather low and fluorescence lifetimes are rather short due to ISC into the triplet state [50][51]. NDIs are reversibly reducible and their stable radical anions absorb in the visible to NIR light range [37]. The aromatic core of NDIs can be easily modified by substituents in
Graphical Abstract
Scheme 1: Synthesis of reference NDI 1 and cNDIs 2–6; bottom: image of saturated solutions of cNDIs 2–6 in DM...
Figure 1: Optical properties of NDI 1 and cNDIs 2 and 6: UV–vis absorbance in CH2Cl2 and in DMF (normal lines...
Scheme 2: Photocatalytic α-alkylation of octanal (12): 500 mM 12, 250 mM 13, 50 mM (20 mol %) organocatalyst ...
Figure 2: Normalized absorbance of cNDI 6 in comparison to normalized emission of the 468 nm, 520 nm, 597 nm,...
Figure 3: Kinetic analysis of yields of product 14 in the presence (solid lines) and in the absence (dashed l...
Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region
- Aude-Héloise Bonardi,
- Frédéric Dumur,
- Guillaume Noirbent,
- Jacques Lalevée and
- Didier Gigmes
Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282
- small part of the wide diversity of possible photoredox catalyst has been presented here. Moreover, wavelength of irradiation is here restricted from 300 to 500 nm. In the recent literature, free radical polymerization using a photoredox catalyst has for example been presented using NIR light with both
Graphical Abstract
Figure 1: Typical oxidative and reductive cycle for a photoredox catalyst (PC).
Figure 2: Transitions involved in absorbing species containing π, σ and n electrons.
Figure 3: Ligand to metal charge transfer (illustrated here for a d6 metal complex).
Figure 4: Metal to ligand charge transfer (illustrated here for a d5 metal complex).
Scheme 1: Structures of additives involved in the photoredox catalytic cycles.
Figure 5: Catalytic cycles involved with iodonium salt and (A) (TMS)3SiH, (B) NVK and (C) EDB.
Scheme 2: Structures of photoredox metal-based catalysts.
Scheme 3: Photocatalytical cycle for the Ru complex.
Scheme 4: Structures of photoredox organocatalysts.
Scheme 5: Diversity of the chemical structures of photoredox organocatalysts.
Scheme 6: Structures of benchmarked monomers.
Scheme 7: Structure of the CARET additive.
Scheme 8: Photoredox catalysis mechanism of a visible light-mediated living radical polymerization. (Abbrevia...
