Protonation of the imino nitrogen deactivates the excited state of imidazolin-5-one in the solid state

  • Ashish Singh
  • Khalid Badi-Uz-Zama
  • Gurunath Ramanathan
Regular Article


The imino nitrogen of p-methoxybenzylideneimidazolinone (pMBDI) was protonated using aqueous \(\hbox {HClO}_{4}\) and HCl acid and crystallized in monoclinic crystal system with \(\textit{P2}_{\textit{1}}/n\) space group. Interestingly, the protonated compounds are fluorescent in polar solvents but non-fluorescent in non-polar solvent as well as in the solid state. These results point to the existence of a non-radiative pathway involving the imidazole nitrogen in the quenching of excited states in these compounds.

Graphical Abstract

SYNOPSIS The imino nitrogen of p-methoxybenzylideneimidazolinone (pMBDI) was protonated and crystallized in monoclinic crystal system with \(\textit{P2}_{\textit{1}}/n\) space group. Interestingly, the protonation at imino nitrogen of imidazolinone ring results in the loss of the fluorescence property of gfp chromophore analogue (p-methoxybenzylideneimidazolinone).


Imidazolin-5-one gfp chromophore fluorescence crystal structure theoretical study 



We are thankful to IIT, Kanpur, India for the financial assistance. A.S. thanks UGC, India for a Junior and a Senior Research Fellowship (JRF & SRF) (Grant No. 20-12/2009(ii) EU-IV).

Supplementary material

12039_2018_1429_MOESM1_ESM.pdf (483 kb)
Supplementary material 1 (pdf 482 KB)


  1. 1.
    (a) Chatterjee T, Roy D, Das A, Ghosh A, Bag P P and Mandal P K 2013 Chemical tweaking of a non-fluorescent GFP chromophore to a highly fluorescent coumarinic fluorophore: application towards photo-uncaging and stem cell imaging RSC Adv. 3 24021; (b) Chen S, Chen Z, Ren W and Ai H 2012 Reaction-based genetically encoded fluorescent hydrogen sulfide sensors J. Am. Chem. Soc. 134 9589; (c) Lippincott-Schwartz J and Patterson G H 2003 Development and use of fluorescent protein markers in living cells Science 300 87; (d) Rosny E and Carpentier P 2012 GFP-like phototransformation mechanisms in the cytotoxic fluorescent protein KillerRed unraveled by structural and spectroscopic investigations J. Am. Chem. Soc. 134 18015; (e) Shi L, Li Y, Liu Z-P, James T D and Long Y-T 2012 Simultaneous determination of Hg(II) and Zn(II) using a GFP inspired chromophore Talanta 100 401; (f) Tsien R Y 1989 Fluorescent probes of cell signaling Annu. Rev. Neurosci. 12 227; (g) Walker C L, Lukyanov K A, Yampolsky I V, Mishin A S, Bommarius A S, Duraj-Thatte A M, Azizi B, Tolbert L M and Solntsev K M 2015 Fluorescence imaging using synthetic GFP chromophores Curr. Opin. Chem. Biol. 27 64; (h) Zimmer M 2002 Green fluorescent protein (GFP): applications, structure, and related photophysical behavior Behavior Chem. Rev. 102 759Google Scholar
  2. 2.
    (a) Dong J, Solntsev K M and Tolbert L M 2006 Solvatochromism of the green fluorescence protein chromophore and its derivatives J. Am. Chem. Soc. 128 12038; (b) Grigorenko B L, Polyakov I V, Savitsky A P and Nemukhin A V 2013 Unusual emitting states of the kindling fluorescent protein: appearance of the cationic chromophore in the GFP family J. Phys. Chem. B 117 7228; (c) He X, Bell A F and Tonge P J 2002 Isotopic labeling and normal-mode analysis of a model green fluorescent protein chromophore J. Phys. Chem. B 106 6056; (d) Joshi H, Upadhyay P, Karia D and Baxi A J 2003 Synthesis of some novel imidazolinones as potent anticonvulsant agents Eur. J. Med. Chem. 38 837CrossRefGoogle Scholar
  3. 3.
    (a) Addison K, Conyard J, Dixon T, Page P C B, Solntsev K M and Meech S R 2012 Ultrafast studies of the photophysics of Cis and Trans states of the green fluorescent protein chromophore J. Phys. Chem. Lett. 3 2298; (b) Kummer A D, Kompa C, Niwa H, Hirano T, Kojima S and Michel-Beyerle M E 2002 Viscosity-dependent fluorescence decay of the GFP chromophore in solution due to fast internal conversion J. Phys. Chem. B 106 7554; (c) Rafiq S, Rajbongshi B K, Nair N N, Sen P and Ramanathan G 2011 Excited state relaxation dynamics of model green fluorescent protein chromophore analogs: evidence for CisTrans isomerism J. Phys. Chem. A 115 13733; (d) Rajbongshi B K, Sen P and Ramanathan G 2010 Twisted intramolecular charge transfer in a model green fluorescent protein luminophore analog Chem. Phys. Lett. 494 295Google Scholar
  4. 4.
    Laptenok S P, Conyard J, Page P C B, Chan Y, You M, Jaffrey S R and Meech S R 2016 Photoacid behaviour in a fluorinated green fluorescent protein chromophore: ultrafast formation of anion and zwitterion states Chem. Sci. 7 5747Google Scholar
  5. 5.
    Chen K-Y, Cheng Y-M, Lai C-H, Hsu C-C, Ho M-L, Lee G-H and Chou P-T 2007 Ortho green fluorescence protein synthetic chromophore; excited-state intramolecular proton transfer via a seven-membered-ring hydrogen-bonding system J. Am. Chem. Soc. 129 4534CrossRefGoogle Scholar
  6. 6.
    Hsieh C-C, Chou P-T, Shih C-W, Chuang W-T, Chung M-W, Lee J and Joo T 2011 Comprehensive studies on an overall proton transfer cycle of the ortho-green fluorescent protein chromophore J. Am. Chem. Soc. 133 2932CrossRefGoogle Scholar
  7. 7.
    (a) Bravaya K B, Khrenova M G, Grigorenko B L, Nemukhin A V and Krylov A I 2011 Effect of protein environment on electronically excited and ionized states of the green fluorescent protein chromophore J. Phys. Chem. B 115 8296; (b) Chang D-H, Ou C-L, Hsu H-Y, Huang G-J, Kao C-Y, Liu Y-H, Peng S-M, Diau E W-G and Yang J-S 2015 Cooperativity and site-selectivity of intramolecular hydrogen bonds on the fluorescence quenching of modified GFP chromophores J. Org. Chem. 80 12431; (c) Huang G-J, Ho J-H, Prabhakar C, Liu Y-H, Peng S-M and Yang J-S 2012 Site-selective hydrogen-bonding-induced fluorescence quenching of highly solvatofluorochromic GFP-like chromophores Org. Lett. 14 5034Google Scholar
  8. 8.
    (a) Cui G, Lan Z and Thiel W 2012 Intramolecular hydrogen bonding plays a crucial role in the photophysics and photochemistry of the GFP chromophore J. Am. Chem. Soc. 134 1662; (b) Huang G-J, Cheng C-W, Hsu H-Y, Prabhakar C, Lee Y-P, Diau E W-G and Yang J-S 2013 Effects of hydrogen bonding on internal conversion of GFP-like chromophores. I. The para-amino systems J. Phys. Chem. B 117 2695Google Scholar
  9. 9.
    (a) Chatterjee T, Mandal M, Das A, Bhattacharyya K, Datta A and Mandal P K 2016 Dual fluorescence in GFP chromophore analogues: chemical modulation of charge transfer and proton transfer bands J. Phys. Chem. B 120 3503; (b) Olsen S 2015 Locally-excited (LE) versus charge-transfer (CT) excited state competition in a series of para-substituted neutral green fluorescent protein (GFP) chromophore models J. Phys. Chem. B 119 2566; (c) Petkova I, Dobrikov G, Banerji N, Duvanel G, Perez R, Dimitrov V, Nikolov P and Vauthey E 2010 Tuning the excited-state dynamics of GFP-inspired imidazolone derivatives J. Phys. Chem. A 114 10; (d) Thor J J V and Sage J T 2006 Charge transfer in green fluorescent protein Photochem. Sci. 5 597Google Scholar
  10. 10.
    (a) Dolgopolova E A, Rice A M, Smith M D and Shustova N B 2016 Photophysics, dynamics, and energy transfer in rigid mimics of GFP based systems Inorg. Chem. 55 7257; (b) Lv X, Yu Y, Zhou M, Hu C, Gao F, Li J, Liu X, Deng K, Zheng P, Gong W, Xia A and Wang J 2015 Ultrafast photoinduced electron transfer in green fluorescent protein bearing a genetically encoded electron acceptor J. Am. Chem. Soc. 137 7270Google Scholar
  11. 11.
    (a) Baranov M S, Solntsev K M, Lukyanova K A and Yampolsky I V 2013 A synthetic approach to GFP chromophore analogs from 3-azidocinnamates: role of methyl rotors in chromophore photophysics Chem. Commun. 49 5778; (b) Bell A F, He X, Wachter R M and Tonge P J 2000 Probing the ground state structure of the green fluorescent protein chromophore using Raman spectroscopy Biochemistry 39 4423; (c) Dong J, Solntsev K M and Tolbert L M 2009 Activation and tuning of green fluorescent protein chromophore emission by alkyl substituent-mediated crystal packing J. Am. Chem. Soc. 131 662; (d) Reynolds J E III, Josowicz M, Tyler P, Vegh R B and Solntsev K M 2013 Spectral and redox properties of the GFP synthetic chromophores as a function of pH in buffered media Chem. Commun. 49 7788; (e) Naumov P e, Kowalik J, Solntsev K M, Baldridge A, Moon J-S, Kranz C and Tolbert L M 2010 Topochemistry and photomechanical effects in crystals of green fluorescent protein-like chromophores: effects of hydrogen bonding and crystal packing J. Am. Chem. Soc. 132 5845; (f) Singh A and Ramanathan G 2017 Red fluorescence protein chromophore inspired selective optical chemosensor for Cu\(^{2+}\) and Hg\(^{2+}\) metal ions J. Lumin. 182 220Google Scholar
  12. 12.
    (a) Dolgopolova E A, Moore T M, Fellows W B, Smith M D and Shustova N B 2016 Photophysics of GFP-related chromophores imposed by a scaffold design Dalton Trans. 45 9884; (b) Xiang S, GuangXi H, Kan L, GuanXin Z and DeQing Z 2013 Tuning the solid-state emission of the analogous GFP chromophore by varying alkyl chains in the imidazolinone ring Sci. China Chem. 56 1197Google Scholar
  13. 13.
    (a) Bhattacharjya G, Savitha G and Ramanathan G 2005 C–H/O interactions are favoured in the crystal structures of imidazolin-5-ones J. Mol. Struct. 752 98; (b) Rajbongshi B K, Nair N N, Nethaji M and Ramanathan G 2012 Segregation into chiral enantiomeric conformations of an achiral molecule by concomitant polymorphism Cryst. Growth Des. 12 1823; (c) Rajbongshi B K and Ramanathan G 2009 Dominant \({\uppi } \ldots {\uppi }\) interaction in the self assemblies of 4-benzylidene imidazolin-5-one analogues J. Chem. Sci. 121 973; (d) Singh A, Rajbongshi B K and Ramanathan G 2014 Tuning of intermolecular interactions results in packing diversity in imidazolin-5-ones J. Chem. Sci. 126 1275Google Scholar
  14. 14.
    Bhattacharjya G, Savitha G and Ramanathan G 2004 Short C=O...C intermolecular contacts for molecular assembly CrystEngComm 6 233CrossRefGoogle Scholar
  15. 15.
    (a) Dolgopolova E A, Williams D E, Greytak A B, Rice A M, Smith M D, Krause J A and Shustova N B 2015 A bio-inspired approach for chromophore communication: ligand-to-ligand and host-to-guest energy transfer in hybrid crystalline scaffolds Angew. Chem. Int. Edit. 54 13639; (b) Fery-Forgues S, Veesler S p, Fellows W B, Tolbert L M and Solntsev K M 2013 Microcrystals with enhanced emission prepared from hydrophobic analogues of the green fluorescent protein chromophore via reprecipitation Langmuir 29 14718; (c) Williams D E, Dolgopolova E A, Pellechia P J, Palukoshka A, Wilson T J, Tan R, Maier J M, Greytak A B, Smith M D, Krause J A and Shustova N B 2015 Mimic of the green fluorescent protein \(\upbeta \)-barrel: photophysics and dynamics of confined chromophores defined by a rigid porous scaffold J. Am. Chem. Soc. 137 2223Google Scholar
  16. 16.
    16. Voityuk A A, Michel-Beyerle M-E and Rosch N 1997 Protonation effects on the chromophore of green fluorescent protein. Quantum chemical study of the absorption spectrum Chem. Phys. Lett. 272 162CrossRefGoogle Scholar
  17. 17.
    Baldridge A, Kowalik J and Tolbert L M 2010 Efficient synthesis of new 4-arylideneimidazolin-5-ones related to the GFP chromophore by 2+3 cyclocondensation of arylideneimines with imidate ylides Synthesis 14 2424Google Scholar
  18. 18.
    Singh A, Rajbongshi B K and Ramanathan G 2015 Introduction of an electron push-pull system yields a planar Red Kaede fluorescence protein chromophore analogue stabilized by a \(\text{ C=O }\ldots \uppi \) interaction J. Chem. Sci. 127 941CrossRefGoogle Scholar
  19. 19.
    Singh A and Ramanathan G 2016 Rational design of heterogeneous silver catalysts by exploitation of counteranion-induced coordination geometry Asian J. Org. Chem. 5 865Google Scholar
  20. 20.
    Frisch M J, Trucks G W, Schlegel H B, Scuseria G E, Robb M A, Cheeseman J R, Scalmani G, Barone V, Mennucci B, Petersson G A, Nakatsuji H, Caricato M, Li X, Hratchian H P, Izmaylov A F, Bloino J, Zheng G, Sonnenberg J L, Hada M, Ehara M, Toyota K, Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao O, Nakai H, Vreven T, Montgomery J A Jr., Peralta J E, Ogliaro F, Bearpark M, Heyd J J, Brothers E, Kudin K N, Staroverov V N, Kobayashi R, Normand J, Raghavachari K, Rendell A, Burant J C, Iyengar S S, Tomasi J, Cossi M, Rega N, Millam J M, Klene M, Knox J E, Cross J B, Bakken V, Adamo C, Jaramillo J, Gomperts R, Stratmann R E, Yazyev O, Austin A J, Cammi R, Pomelli C, Ochterski J W, Martin R L, Morokuma K, Zakrzewski V G, Voth G A, Salvador P, Dannenberg J J, Dapprich S, Daniels A D, Farkas Ö, Foresman J B, Ortiz J V, Cioslowski J and Fox D J, Gaussian Inc., Wallingford, CT 2009 Gaussian 09, Revision D.01, Gaussian, Inc., Wallingford, CTGoogle Scholar
  21. 21.
    (a) Becke A D 1993 Density-functional thermochemistry. III. The role of exact exchange J. Chem. Phys. 98 5648; (b) Gautam P, Misra R, Siddiqui S A and Sharma G D 2015 Unsymmetrical donor-acceptor-acceptor-\({\uppi }\)-donor type benzothiadiazole-based small molecule for a solution processed bulk heterojunction organic solar cell ACS Appl. Mater. Interfaces 7 10283Google Scholar
  22. 22.
    Xavier T S, Rashid N and Joe I H 2011 Vibrational spectra and DFT study of anticancer active molecule 2-(4-bromophenyl)-1H-benzimidazole by normal coordinate analysis Spectrochim. Acta Part A 78 319CrossRefGoogle Scholar

Copyright information

© Indian Academy of Sciences 2018

Authors and Affiliations

  1. 1.Department of ChemistryIndian Institute of Technology KanpurKanpurIndia

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