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  • Review Article
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Heteroaryl azo dyes as molecular photoswitches

Nature Reviews Chemistry volume 3, pages 133–146 (2019)Cite this article

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Abstract

We have known of azobenzene for over 150 years, the past 80 of which have seen the study and application of its photochromism. Azobenzene derivatives are now considered archetypical molecular switches, and their stability and reliability make them amenable to many fields of modern chemistry, materials science, biology and photopharmacology. When developing a photoswitch for a given application, a common approach is to tune the properties of an azobenzene. It is also possible to instead use heteroaryl azo dyes — motifs that are less popular even though their diversity offers distinct features. Despite the first discoveries of switching behaviour in heteroaryl azos and azobenzenes being coincident, the former have only recently begun to attract attention. This Review describes how the versatile and multifaceted characteristics of these scaffolds make them serious alternatives to azobenzene derivatives in molecular photoactuation. Heteroaryl azo photoswitches arguably deserve more consideration, and our survey of these systems includes challenges to their successful deployment.

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Fig. 1: Photophysical and photochemical properties of heteroaryl azoswitches.
Fig. 2: Thermal Z→E isomerization features in heteroaryl azoswitches.
Fig. 3: Azos with aromatic rings containing one N atom.
Fig. 4: Azos with aromatic rings containing two N atoms.
Fig. 5: Azophotoswitches based on arenes containing more than two heteroatoms.

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References

  1. Griess, P. Vorläufige Notiz über die Einwirkung von salpetriger Säure auf Amidinitro- und Aminitrophenylsäure [German]. Ann. Chem. Pharm. 106, 123–125 (1858).

    Article  Google Scholar 

  2. Wizinger-Aust, R. Peter Griess und seine Zeit [German]. Angew. Chem. 70, 199–204 (1958).

    Article  Google Scholar 

  3. Hunger, K. & Herbst, W. in Ullmann’s Encyclopedia of Industrial Chemistry (Wiley-VCH, 2000).

  4. Hunger, K. et al. in Ullmann’s Encyclopedia of Industrial Chemistry (Wiley-VCH, 2000).

  5. Domagk, G. Ein beitrag zur chemotherapie der bakteriellen Infektionen [German]. Dtsch. Med. Wochenschr. 61, 250–253 (1935).

    Article  CAS  Google Scholar 

  6. Kirpal, A. & Böhm, W. Über eine neuartige Isomerie in der Pyridin-Reihe (I. Mitteil.) [German]. Berichte Dtsch. Chem. Ges. B Ser. 65, 680–682 (1932).

    Google Scholar 

  7. Hartley, G. S. The cis-form of azobenzene. Nature 140, 281 (1937).

    Article  CAS  Google Scholar 

  8. Le Fèvre, R. J. W. & Worth, C. V. 397. Indications of geometrical isomerism with 2:2ʹ-azopyridine. J. Chem. Soc. 1951, 1814–1817 (1951).

    Article  Google Scholar 

  9. Campbell, N., Henderson, A. W. & Taylor, D. 257. Geometrical isomerism of azo-compounds. J. Chem. Soc. 1953, 1281–1285 (1953).

    Article  Google Scholar 

  10. Dhammika Bandara, H. M. & Burdette, S. C. Photoisomerization in different classes of azobenzene. Chem. Soc. Rev. 41, 1809–1825 (2012).

    Article  Google Scholar 

  11. Bléger, D. & Hecht, S. Visible-light-activated molecular switches. Angew. Chem. Int. Ed. 54, 11338–11349 (2015).

    Article  CAS  Google Scholar 

  12. Dong, M., Babalhavaeji, A., Samanta, S., Beharry, A. A. & Woolley, G. A. Red-shifting azobenzene photoswitches for in vivo use. Acc. Chem. Res. 48, 2662–2670 (2015).

    Article  CAS  PubMed  Google Scholar 

  13. Velema, W. A., Szymanski, W. & Feringa, B. L. Photopharmacology: beyond proof of principle. J. Am. Chem. Soc. 136, 2178–2191 (2014).

    Article  CAS  PubMed  Google Scholar 

  14. Wegener, M., Hansen, M. J., Driessen, A. J. M., Szymanski, W. & Feringa, B. L. Photocontrol of antibacterial activity: shifting from UV to red light activation. J. Am. Chem. Soc. 139, 17979–17986 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Garcia-Amorós, J., Sánchez-Ferrer, A., Massad, W. A., Nonell, S. & Velasco, D. Kinetic study of the fast thermal cis-to-trans isomerisation of para-. ortho- and polyhydroxyazobenzenes. Phys. Chem. Chem. Phys. 12, 13238–13242 (2010).

    Article  PubMed  CAS  Google Scholar 

  16. Dokic´, J. et al. Quantum chemical investigation of thermal cis-to-trans isomerization of azobenzene derivatives: substituent effects, solvent effects, and comparison to experimental data. J. Phys. Chem. A 113, 6763–6773 (2009).

    Article  PubMed  CAS  Google Scholar 

  17. Knie, C. et al. ortho-fluoroazobenzenes: visible light switches with very long-lived Z isomers. Chem. Eur. J. 20, 16492–16501 (2014).

    Article  CAS  PubMed  Google Scholar 

  18. Beharry, A. A., Sadovski, O. & Woolley, G. A. Azobenzene photoswitching without ultraviolet light. J. Am. Chem. Soc. 133, 19684–19687 (2011).

    Article  CAS  PubMed  Google Scholar 

  19. Samanta, S. et al. Photoswitching azo compounds in vivo with red light. J. Am. Chem. Soc. 135, 9777–9784 (2013).

    Article  CAS  PubMed  Google Scholar 

  20. Gelebart, A. H. et al. Making waves in a photoactive polymer film. Nature 546, 632–636 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  21. Banghart, M., Borges, K., Isacoff, E., Trauner, D. & Kramer, R. H. Light-activated ion channels for remote control of neuronal firing. Nat. Neurosci. 7, 1381–1386 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Hvilsted, S., Sánchez, C. & Alcalá, R. The volume holographic optical storage potential in azobenzene containing polymers. J. Mater. Chem. 19, 6641–6648 (2009).

    Article  CAS  Google Scholar 

  23. Frasconi, M. & Mazzei, F. Electrochemically controlled assembly and logic gates operations of gold nanoparticle arrays. Langmuir 28, 3322–3331 (2012).

    Article  CAS  PubMed  Google Scholar 

  24. García-Amorós, J. & Velasco, D. Recent advances towards azobenzene-based light-driven real-time information-transmitting materials. Beilstein J. Org. Chem. 8, 1003–1017 (2012).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  25. Siewertsen, R. et al. Highly efficient reversible Z−E photoisomerization of a bridged azobenzene with visible light through resolved S1 (nπ*) absorption bands. J. Am. Chem. Soc. 131, 15594–15595 (2009).

    Article  CAS  PubMed  Google Scholar 

  26. Chen, S., Zhang, Y., Chen, K., Yin, Y. & Wang, C. Insight into a fast-phototuning azobenzene switch for sustainably tailoring the foam stability. ACS Appl. Mater. Interfaces 9, 13778–13784 (2017).

    Article  CAS  PubMed  Google Scholar 

  27. Feringa, B. L. & Browne, W. R. (eds) Molecular Switches 2nd edn (Wiley-VCH, Weinheim, 2011).

  28. Weston, C. E., Richardson, R. D., Haycock, P. R., White, A. J. P. & Fuchter, M. J. Arylazopyrazoles: azoheteroarene photoswitches offering quantitative isomerization and long thermal half-lives. J. Am. Chem. Soc. 136, 11878–11881 (2014).

    Article  CAS  PubMed  Google Scholar 

  29. Calbo, J. et al. Tuning azoheteroarene photoswitch performance through heteroaryl design. J. Am. Chem. Soc. 139, 1261–1274 (2017).

    Article  CAS  PubMed  Google Scholar 

  30. Brown, E. V. & Granneman, G. R. Cis–trans isomerism in the pyridyl analogs of azobenzene. Kinetic and molecular orbital analysis. J. Am. Chem. Soc. 97, 621–627 (1975).

    Article  CAS  Google Scholar 

  31. Suwa, K., Otsuki, J. & Goto, K. Syntheses of shuttlecock- and bowl-equipped phenylazopyridines and photomodulation of their coordination ability to Zn-porphyrin. Tetrahedron Lett. 50, 2106–2108 (2009).

    Article  CAS  Google Scholar 

  32. Otsuki, J., Suwa, K., Sarker, K. K. & Sinha, C. Photoisomerization and thermal isomerization of arylazoimidazoles. J. Phys. Chem. A 111, 1403–1409 (2007).

    Article  CAS  PubMed  Google Scholar 

  33. Travieso-Puente, R. et al. Arylazoindazole photoswitches: facile synthesis and functionalization via SNAr substitution. J. Am. Chem. Soc. 139, 3328–3331 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Cechová, L. et al. Photoswitching behavior of 5-phenylazopyrimidines: in situ irradiation NMR and optical spectroscopy combined with theoretical methods. J. Org. Chem. 83, 5986–5998 (2018).

    Article  PubMed  CAS  Google Scholar 

  35. Simeth, N. A., Crespi, S., Fagnoni, M. & König, B. Tuning the thermal isomerization of phenylazoindole photoswitches from days to nanoseconds. J. Am. Chem. Soc. 140, 2940–2946 (2018).

    Article  CAS  PubMed  Google Scholar 

  36. Wang, L., Yi, C., Zou, H., Xu, J. & Xu, W. Theoretical study on the isomerization mechanisms of phenylazopyridine on S0 and S1 states. J. Phys. Org. Chem. 22, 888–896 (2009).

    Article  CAS  Google Scholar 

  37. Casellas, J., Alcover-Fortuny, G., de Graaf, C. & Reguero, M. Phenylazopyridine as switch in photochemical reactions. A detailed computational description of the mechanism of its photoisomerization. Mater 10, 1342 (2017).

    Article  CAS  Google Scholar 

  38. Demchenko, A. P., Tomin, V. I. & Chou, P.-T. Breaking the Kasha rule for more efficient photochemistry. Chem. Rev. 117, 13353–13381 (2017).

    Article  CAS  PubMed  Google Scholar 

  39. Tongying, P., Yoopensuk, S., Leesakul, N. & Tantirungrotechai, Y. Exploring photochemistry of 2-(phenylazo)pyridine dye by using TDDFT/DFT methods. Can. J. Chem. Eng. 90, 860–864 (2012).

    Article  CAS  Google Scholar 

  40. Zhao, L., Liu, J. & Zhou, P. Effect of methylation on the photodynamical behavior of arylazoimidazoles: new insight from theoretical ab initio potential energy calculations and molecular dynamics simulations. J. Phys. Chem. A 121, 141–150 (2017).

    Article  CAS  PubMed  Google Scholar 

  41. Yin, T.-T., Zhao, Z.-X. & Zhang, H.-X. A theoretical study on the thermal cis–trans isomerization of azoheteroarene photoswitches. New J. Chem. 41, 1659–1669 (2017).

    Article  CAS  Google Scholar 

  42. Garcia-Amorós, J., Díaz-Lobo, M., Nonell, S. & Velasco, D. Fastest thermal isomerization of an azobenzene for nanosecond photoswitching applications under physiological conditions. Angew. Chem. Int. Ed. 51, 12820–12823 (2012).

    Article  CAS  Google Scholar 

  43. Garcia-Amorós, J., Nonell, S. & Velasco, D. Photo-driven optical oscillators in the kHz range based on push–pull hydroxyazopyridines. Chem. Commun. 47, 4022–4024 (2011).

    Article  CAS  Google Scholar 

  44. Garcia-Amorós, J., Nonell, S. & Velasco, D. Light-controlled real time information transmitting systems based on nanosecond thermally-isomerising amino-azopyridinium salts. Chem. Commun. 48, 3421–3423 (2012).

    Article  CAS  Google Scholar 

  45. Kirpal, A. Über Azo-pyridine [German]. Ber. Dtsch. Chem. Ges. 67, 70–71 (1934).

    Article  Google Scholar 

  46. Nakagawa, M., Rikukawa, M., Watanabe, M., Sanui, K. & Ogata, N. Electrochemical and photochromic properties of azopyridinium methylsulfates. Chem. Lett. 23, 1785–1788 (1994).

    Article  Google Scholar 

  47. Nakagawa, M., Rikukawa, M., Watanabe, M., Sanui, K. & Ogata, N. Photochromic, electrochemical, and photoelectrochemical properties of novel azopyridinium derivatives. Bull. Chem. Soc. Jpn 70, 737–744 (1997).

    Article  CAS  Google Scholar 

  48. Pourrieux, G. et al. Electron-, proton-, and photon-induced spectroscopic changes in chromophore-quencher tricarbonyl(2,2ʹ-bipyridine)rhenium(i) complexes with 4,4ʹ-azobis(pyridine). Inorg. Chem. 49, 4084–4091 (2010).

    Article  CAS  PubMed  Google Scholar 

  49. Bardají, M., Barrio, M. & Espinet, P. Photosensitive azobispyridine gold(i) and silver(i) complexes. Dalton Trans. 40, 2570–2577 (2011).

    Article  PubMed  CAS  Google Scholar 

  50. Zhou, Q.-X. et al. A novel azopyridine-based Ru(ii) complex with GSH-responsive DNA photobinding ability. Chem. Commun. 51, 10684–10686 (2015).

    Article  CAS  Google Scholar 

  51. Telleria, A. et al. Azobenzene-appended bis-cyclometalated iridium(iii) bipyridyl complexes. Organometallics 34, 5513–5529 (2015).

    Article  CAS  Google Scholar 

  52. Busby, M., Matousek, P., Towrie, M. & Vlc˘ek, A. Ultrafast excited-state dynamics of photoisomerizing complexes fac-[Re(Cl)(CO)3(papy)2] and fac-[Re(papy)(CO)3(bpy)]+ (papy = trans-4-phenylazopyridine). Inorg. Chim. Acta 360, 885–896 (2007).

    Article  CAS  Google Scholar 

  53. Ragon, F. et al. Thermal spin crossover behaviour of two-dimensional Hofmann-type coordination polymers incorporating photoactive ligands. Aust. J. Chem. 67, 1563–1573 (2014).

    Article  CAS  Google Scholar 

  54. Otsuki, J., Harada, K. & Araki, K. Supramolecular electro- and proto-photoswitch. Chem. Lett. 28, 269–270 (1999).

    Article  Google Scholar 

  55. Otsuki, J. & Narutaki, K. Photochromism of phenylazopyridines and its application to the fluorescence modulation of zinc–porphyrins. Bull. Chem. Soc. Jpn 77, 1537–1544 (2004).

    Article  CAS  Google Scholar 

  56. Otsuki, J., Narutaki, K. & Bakke, J. M. Light-triggered luminescence modulation using labile axial coordination to zinc–porphyrin. Chem. Lett. 33, 356–357 (2004).

    Article  CAS  Google Scholar 

  57. Wang, Y. et al. Switching single azopyridine supramolecules in ordered arrays on Au(111). J. Am. Chem. Soc. 132, 1196–1197 (2010).

    Article  CAS  PubMed  Google Scholar 

  58. Matino, F. et al. Single azopyridine-substituted porphyrin molecules for configurational and electronic switching. Chem. Commun. 46, 6780–6782 (2010).

    Article  CAS  Google Scholar 

  59. Thies, S. et al. Light-induced spin change by photodissociable external ligands: a new principle for magnetic switching of molecules. J. Am. Chem. Soc. 133, 16243–16250 (2011).

    Article  CAS  PubMed  Google Scholar 

  60. Thies, S. et al. Light-driven coordination-induced spin-state switching: rational design of photodissociable ligands. Chem. Eur. J. 18, 16358–16368 (2012).

    Article  CAS  PubMed  Google Scholar 

  61. Venkataramani, S. et al. Magnetic bistability of molecules in homogeneous solution at room temperature. Science 331, 445–448 (2011).

    Article  CAS  PubMed  Google Scholar 

  62. Dommaschk, M. et al. Photoswitchable magnetic resonance imaging contrast by improved light-driven coordination-induced spin state switch. J. Am. Chem. Soc. 137, 7552–7555 (2015).

    Article  CAS  PubMed  Google Scholar 

  63. Bannwarth, A. et al. Feiii spin-crossover complexes with photoisomerizable ligands: experimental and theoretical studies on the ligand-driven light-induced spin change effect. Eur. J. Inorg. Chem. 2012, 2776–2783 (2012).

    Article  CAS  Google Scholar 

  64. Garcia-Amorós, J., Massad, W. A., Nonell, S. & Velasco, D. Fast isomerizing methyl iodide azopyridinium salts for molecular switches. Org. Lett. 12, 3514–3517 (2010).

    Article  PubMed  CAS  Google Scholar 

  65. Garcia-Amorós, J. et al. Spatially close azo dyes with sub-nanosecond switching speeds and exceptional temporal resolution. Chem. Eur. J. 21, 14292–14296 (2015).

    Article  PubMed  CAS  Google Scholar 

  66. Yu, Y., Nakano, M. & Ikeda, T. Directed bending of a polymer film by light. Nature 425, 145 (2003).

    Article  CAS  PubMed  Google Scholar 

  67. Devi, S., Saraswat, M., Grewal, S. & Venkataramani, S. Evaluation of substituent effect in Z-isomer stability of arylazo-1H-3,5-dimethylpyrazoles: interplay of steric, electronic effects and hydrogen bonding. J. Org. Chem. 83, 4307–4322 (2018).

    Article  CAS  PubMed  Google Scholar 

  68. Poutanen, M., Ahmed, Z., Rautkari, L., Ikkala, O. & Priimagi, A. Thermal isomerization of hydroxyazobenzenes as a platform for vapor sensing. ACS Macro Lett. 7, 381–386 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  69. Raposo, M. M. M., Sousa, A. M. R. C., Fonseca, A. M. C. & Kirsch, G. Thienylpyrrole azo dyes: synthesis, solvatochromic and electrochemical properties. Tetrahedron 61, 8249–8256 (2005).

    Article  CAS  Google Scholar 

  70. Raposo, M. M. M., Castro, M. C. R., Fonseca, A. M. C., Schellenberg, P. & Belsley, M. Design, synthesis, and characterization of the electrochemical, nonlinear optical properties, and theoretical studies of novel thienylpyrrole azo dyes bearing benzothiazole acceptor groups. Tetrahedron 67, 5189–5198 (2011).

    Article  CAS  Google Scholar 

  71. Coelho, P. J., Carvalho, L. M., Fonseca, A. M. C. & Raposo, M. M. M. Photochromic properties of thienylpyrrole azo dyes in solution. Tetrahedron Lett. 47, 3711–3714 (2006).

    Article  CAS  Google Scholar 

  72. Coelho, P. J., Castro, M. C. R., Fonseca, A. M. C. & Raposo, M. M. M. Photoswitching in azo dyes bearing thienylpyrrole and benzothiazole heterocyclic systems. Dyes Pigm. 92, 745–748 (2012).

    Article  CAS  Google Scholar 

  73. Coelho, P. J., Sousa, C. M., Castro, M. C. R., Fonseca, A. M. C. & Raposo, M. M. M. Fast thermal cis–trans isomerization of heterocyclic azo dyes in PMMA polymers. Opt. Mater. 35, 1167–1172 (2013).

    Article  CAS  Google Scholar 

  74. Raposo, M. M. M. et al. Synthesis and characterization of novel diazenes bearing pyrrole, thiophene and thiazole heterocycles as efficient photochromic and nonlinear optical (NLO) materials. Dyes Pigm. 91, 62–73 (2011).

    Article  CAS  Google Scholar 

  75. Garcia-Amorós, J. et al. New heterocyclic systems to afford microsecond green-light isomerisable azo dyes and their use as fast molecular photochromic switches. Chem. Commun. 49, 11427–11429 (2013).

    Article  CAS  Google Scholar 

  76. Garcia-Amorós, J. et al. Molecular photo-oscillators based on highly accelerated heterocyclic azo dyes in nematic liquid crystals. Chem. Commun. 50, 6704–6706 (2014).

    Article  Google Scholar 

  77. Whittaker, N. & Jones, T. S. G. 354. A new synthesis and the chemical properties of 5-aminopyrimidine. J. Chem. Soc. 1951, 1565–1570 (1951).

    Article  Google Scholar 

  78. Bártová, K. et al. Influence of intramolecular charge transfer and nuclear quantum effects on intramolecular hydrogen bonds in azopyrimidines. J. Org. Chem. 82, 10350–10359 (2017).

    Article  PubMed  CAS  Google Scholar 

  79. Procházková, E. et al. Photoswitchable intramolecular hydrogen bonds in 5-phenylazopyrimidines revealed by in situ irradiation NMR spectroscopy. Chem. Eur. J. 24, 492–498 (2018).

    Article  PubMed  CAS  Google Scholar 

  80. Wang, Y.-T., Liu, X.-Y., Cui, G., Fang, W.-H. & Thiel, W. Photoisomerization of arylazopyrazole photoswitches: stereospecific excited-state relaxation. Angew. Chem. Int. Ed. 55, 14009–14013 (2016).

    Article  CAS  Google Scholar 

  81. Weingart, O., Lan, Z., Koslowski, A. & Thiel, W. Chiral pathways and periodic decay in cis-azobenzene photodynamics. J. Phys. Chem. Lett. 2, 1506–1509 (2011).

    Article  CAS  Google Scholar 

  82. Weston, C. E. et al. Toward photopharmacological antimicrobial chemotherapy using photoswitchable amidohydrolase inhibitors. ACS Infect. Dis. 3, 152–161 (2017).

    Article  CAS  PubMed  Google Scholar 

  83. Stricker, L., Böckmann, M., Kirse, T., Doltsinis, N. & Ravoo, B. J. Arylazopyrazole photoswitches in aqueous solution: substituent effects, photophysical properties and host–guest chemistry. Chem. Eur. J. 24, 8639–8647 (2018).

    Article  CAS  PubMed  Google Scholar 

  84. Adam, V. et al. Expanding the toolbox of photoswitches for DNA nanotechnology using arylazopyrazoles. Chem. Eur. J. 24, 1062–1066 (2018).

    Article  CAS  PubMed  Google Scholar 

  85. Ghebreyessus, K. & Cooper, S. M. Photoswitchable arylazopyrazole-based ruthenium(ii) arene complexes. Organometallics 36, 3360–3370 (2017).

    Article  CAS  Google Scholar 

  86. Wiemann, M. et al. Photo-responsive bioactive surfaces based on cucurbit[8]uril-mediated host–guest interactions of arylazopyrazoles. Chem. Eur. J. 24, 813–817 (2018).

    Article  CAS  PubMed  Google Scholar 

  87. Stricker, L., Fritz, E.-C., Peterlechner, M., Doltsinis, N. L. & Ravoo, B. J. Arylazopyrazoles as light-responsive molecular switches in cyclodextrin-based supramolecular systems. J. Am. Chem. Soc. 138, 4547–4554 (2016).

    Article  CAS  PubMed  Google Scholar 

  88. Bull, J. N., Scholz, M. S., Coughlan, N. J. A., Kawai, A. & Bieske, E. J. Monitoring isomerization of molecules in solution using ion mobility mass spectrometry. Anal. Chem. 88, 11978–11981 (2016).

    Article  CAS  PubMed  Google Scholar 

  89. Wendler, T., Schütt, C., Näther, C. & Herges, R. Photoswitchable azoheterocycles via coupling of lithiated imidazoles with benzenediazonium salts. J. Org. Chem. 77, 3284–3287 (2012).

    Article  CAS  PubMed  Google Scholar 

  90. Otsuki, J. et al. Photochromism of 2-(phenylazo)imidazoles. J. Phys. Chem. A 109, 8064–8069 (2005).

    Article  CAS  PubMed  Google Scholar 

  91. Fukuda, N., Kim, J. Y., Fukuda, T., Ushijima, H. & Tamada, K. Synthesis and optical characterization of novel imidazole-based azo materials. Jpn. J. Appl. Phys. 45, 460–464 (2006).

    Article  CAS  Google Scholar 

  92. Endo, M., Nakayama, K., Kaida, Y. & Majima, T. Photoisomerization of 2ʹ-deoxyribofuranosyl and ribofuranosyl 2-phenylazoimidazole. Tetrahedron Lett. 44, 6903–6906 (2003).

    Article  CAS  Google Scholar 

  93. Mondal, J. A., Saha, G., Sinha, C. & Palit, D. K. Photoisomerization dynamics of N-1-methyl-2-(tolylazo) imidazole and the effect of complexation with Cu(ii). Phys. Chem. Chem. Phys. 14, 13027–13034 (2012).

    Article  CAS  PubMed  Google Scholar 

  94. Heitmann, G., Schütt, C. & Herges, R. Spin state switching in solution with an azoimidazole-functionalized nickel(ii)-porphyrin. Eur. J. Org. Chem. 2016, 3817–3823 (2016).

    Article  CAS  Google Scholar 

  95. Weston, C. E., Richardson, R. D. & Fuchter, M. J. Photoswitchable basicity through the use of azoheteroarenes. Chem. Commun. 52, 4521–4524 (2016).

    Article  CAS  Google Scholar 

  96. Bull, J. N., Scholz, M. S., Coughlan, N. J. A. & Bieske, E. J. Isomerisation of an intramolecular hydrogen-bonded photoswitch: protonated azobis(2-imidazole). Phys. Chem. Chem. Phys. 19, 12776–12783 (2017).

    Article  CAS  PubMed  Google Scholar 

  97. Rennhack, A., Grahn, E., Kaupp, U. B. & Berger, T. K. Photocontrol of the Hv1 proton channel. ACS Chem. Biol. 12, 2952–2957 (2017).

    Article  CAS  PubMed  Google Scholar 

  98. Araki, S., Hirose, S., Konishi, Y., Nogura, M. & Hirashita, T. Synthesis of 3-(phenylazo)-1,2,4-triazoles by a nucleophilic reaction of primary amines with 5-chloro-2,3-diphenyltetrazolium salt via mesoionic 2,3-diphenyltetrazolium-5-aminides. Beilstein J. Org. Chem. 5, 8 (2009).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  99. Li, Y.-C. et al. 1,1ʹ-Azobis-1,2,3-triazole: a high-nitrogen compound with Stable N8 structure and photochromism. J. Am. Chem. Soc. 132, 12172–12173 (2010).

    Article  CAS  PubMed  Google Scholar 

  100. Klapötke, T. M. & Piercey, D. G. 1,1ʹ-Azobis(tetrazole): a highly energetic nitrogen-rich compound with a N10 chain. Inorg. Chem. 50, 2732–2734 (2011).

    Article  PubMed  CAS  Google Scholar 

  101. Klapötke, T. M., Krumm, B., Martin, F. A. & Stierstorfer, J. New azidotetrazoles: structurally interesting and extremely sensitive. Chem. Asian J. 7, 214–224 (2012).

    Article  PubMed  CAS  Google Scholar 

  102. Tang, Y. et al. Synthesis and characterization of a stable, catenated N11 energetic salt. Angew. Chem. Int. Ed. 52, 4875–4877 (2013).

    Article  CAS  Google Scholar 

  103. Ferreira, R., Nilsson, J. R., Solano, C., Andréasson, J. & Grøtli, M. Design, synthesis and inhibitory activity of photoswitchable RET kinase inhibitors. Sci. Rep. 5, 9769 (2015).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  104. Kolarski, D., Szymanski, W. & Feringa, B. L. Two-step, one-pot synthesis of visible-light-responsive 6-azopurines. Org. Lett. 19, 5090–5093 (2017).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  105. Raposo, M. M. M., Ferreira, A. M. F. P., Belsley, M. & Moura, J. C. V. P. 5ʹ-Alkoxy-2,2ʹ-bithiophene azo dyes: a novel promising series of NLO-chromophores. Tetrahedron 64, 5878–5884 (2008).

    Article  CAS  Google Scholar 

  106. Raposo, M. M. M., Castro, M. C. R., Belsley, M. & Fonseca, A. M. C. Push–pull bithiophene azo-chromophores bearing thiazole and benzothiazole acceptor moieties: synthesis and evaluation of their redox and nonlinear optical properties. Dyes Pigm. 91, 454–465 (2011).

    Article  CAS  Google Scholar 

  107. Coelho, P. J., Carvalho, L. M., Moura, J. C. V. P. & Raposo, M. M. M. Novel photochromic 2,2ʹ-bithiophene azo dyes. Dyes Pigm. 82, 130–133 (2009).

    Article  CAS  Google Scholar 

  108. El-Shishtawy, R. M. et al. Thiazole azo dyes with lateral donor branch: synthesis, structure and second order NLO properties. Dyes Pigm. 96, 45–51 (2013).

    Article  CAS  Google Scholar 

  109. Coelho, P. J., Castro, M. C. R., Fernandes, S. S. M., Fonseca, A. M. C. & Raposo, M. M. M. Enhancement of the photochromic switching speed of bithiophene azo dyes. Tetrahedron Lett. 53, 4502–4506 (2012).

    Article  CAS  Google Scholar 

  110. Crespi, S., Simeth, N. A., Bellisario, A., Fagnoni, M. & König, B. Unraveling the thermal isomerization mechanisms of heteroaryl azoswitches: phenylazoindoles as case study. SSRN Electron. J. https://doi.org/10.2139/ssrn.3271628 (2018).

    Article  Google Scholar 

  111. Xu, Y., Gao, C., Andréasson, J. & Grøtli, M. Synthesis and photophysical characterization of azoheteroarenes. Org. Lett. 20, 4875–4879 (2018).

    Article  CAS  PubMed  Google Scholar 

  112. Gavkus, D. N., Maiorova, O. A., Borisov, M. Y. & Egorova, A. Y. Azo coupling of 5-substituted furan-2(3H)-ones and 1H-pyrrol-2(3H)-ones with arene(hetarene)diazonium salts. Russ. J. Org. Chem. 48, 1229–1232 (2012).

    Article  CAS  Google Scholar 

  113. Hamama, W. S., Ibrahim, M. E. & Zoorob, H. H. Synthesis and biological evaluation of some novel isoxazole derivatives: isoxazole with basic side chain. J. Heterocycl. Chem. 54, 341–346 (2017).

    Article  CAS  Google Scholar 

  114. Sherif, S., Ekladious, L. & Abd Elmalek, G. The synthesis of some azo dyes containing the quinoxaline nucleus. I. J. Prakt. Chem 312, 759–766 (1970).

    Article  CAS  Google Scholar 

  115. Rangnekar, D. W. & Tagdiwala, P. V. Synthesis of azo dyes from 6-amino-2-methoxy-quinoxaline and their use as disperse dyes for polyester fibres. Dyes Pigm. 8, 151–156 (1987).

    Article  CAS  Google Scholar 

  116. Nenov, A. et al. UV-light-induced vibrational coherences: the key to understand Kasha rule violation in trans-azobenzene. J. Phys. Chem. Lett. 9, 1534–1541 (2018).

    Article  CAS  PubMed  Google Scholar 

  117. Yu, L., Xu, C. & Zhu, C. Probing the π → π* photoisomerization mechanism of cis-azobenzene by multi-state ab initio on-the-fly trajectory dynamics simulation. Phys. Chem. Chem. Phys. 17, 17646–17660 (2015).

    Article  CAS  PubMed  Google Scholar 

  118. Diau, E. W.-G. A. New trans-to-cis photoisomerization mechanism of azobenzene on the S1(n, π*) surface. J. Phys. Chem. A 108, 950–956 (2004).

    Article  CAS  Google Scholar 

  119. Conti, I., Garavelli, M. & Orlandi, G. The different photoisomerization efficiency of azobenzene in the lowest nπ* and ππ* singlets: the role of a phantom state. J. Am. Chem. Soc. 130, 5216–5230 (2008).

    Article  CAS  PubMed  Google Scholar 

  120. Xu, C., Yu, L., Gu, F. L. & Zhu, C. Probing the π → π* photoisomerization mechanism of trans-azobenzene by multi-state ab initio on-the-fly trajectory dynamics simulations. Phys. Chem. Chem. Phys. 20, 23885–23897 (2018).

    Article  CAS  PubMed  Google Scholar 

  121. Tan, E. M. M. et al. Fast photodynamics of azobenzene probed by scanning excited-state potential energy surfaces using slow spectroscopy. Nat. Commun. 6, 5860 (2015).

    Article  PubMed  Google Scholar 

  122. Tavadze, P. et al. A machine-driven hunt for global reaction coordinates of azobenzene photoisomerization. J. Am. Chem. Soc. 140, 285–290 (2018).

    Article  CAS  PubMed  Google Scholar 

  123. Rau, H. Further evidence for rotation in the π,π* and inversion in the n,π* photoisomerization of azobenzenes. J. Photochem. 26, 221–225 (1984).

    Article  CAS  Google Scholar 

  124. Bortolus, P. & Monti, S. Cis ⇄ trans photoisomerization of azobenzene–cyclodextrin inclusion complexes. J. Phys. Chem. 91, 5046–5050 (1987).

    Article  CAS  Google Scholar 

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Acknowledgements

S.C. thanks D. Ravelli and R. Tinelli for fruitful discussions. N.A.S. thanks the Studienstiftung des Deutschen Volkes for a PhD scholarship.

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  1. Institute for Organic Chemistry, Department of Chemistry and Pharmacy, University of Regensburg, Regensburg, Germany

    Stefano Crespi, Nadja A. Simeth & Burkhard König

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Contributions

S.C. and N.A.S. contributed equally to the preparation of this manuscript. S.C. and N.A.S. researched data for the article and contributed to the discussion of content and writing. B.K. contributed to the discussion, writing, reviewing and editing of the manuscript before submission.

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Correspondence to Burkhard König.

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Glossary

Photopharmacology

The use of light to control the activity of biologically relevant species used as molecular tools, drugs or prodrugs.

Photoswitch

A molecule that can be reversibly isomerized between two (or more) states using light irradiation. The return to the first state, which is typically more thermally stable, can occur either photochemically or thermally, depending on the type of molecule.

Kasha’s rule

A general rule that relates to molecules that can be excited to different states of the same spin multiplicity. Of these different states, it is the lower state that emits a photon or engages in reactivity. Thus, the photophysical/photochemical behaviour of a molecule is, to some extent, independent of the wavelength used to excite it

Photochromism

The light-triggered interconversion between two chemical species with different absorption spectra. The two species typically have distinct structural and electronic properties.

Conical intersection

The crossing point between two electronic states of the same multiplicity. A polyatomic species with N nuclei can thus have two hypersurfaces of the same spatial symmetry, which cross in a (3N − 8)-dimensional subspace of the (3N − 6)-nuclear coordinate space.

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Crespi, S., Simeth, N.A. & König, B. Heteroaryl azo dyes as molecular photoswitches. Nat Rev Chem 3, 133–146 (2019). https://doi.org/10.1038/s41570-019-0074-6

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