Synthesis and optical properties of new 2-(5-arylpyridine-2-yl)-6-(het)arylquinoline-based “push-pull” fluorophores

Article abstract of DOI:10.1016/j.dyepig.2019.04.029

2-(5-Arylpyridine-2-yl)-6-(het)arylquinoline-based “push-pull” fluorophores were synthesized by means of the heterocyclization reaction between the corresponding isonitrosoacetophenone hydrazones and 6-bromoquinoline-2-carboxaldehyde followed by an aza-Diels-Alder/Suzuki cross-coupling reaction sequence. The optical properties of the obtained fluorophores were studied and the non-linear optic behavior for the two most representative ones were confirmed based on the solvatochromic experiments.

Full text of DOI:10.1016/j.dyepig.2019.04.029

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Synthesis and optical properties of new 2-(5-arylpyridine-2-yl)-6-(het)arylquinoline-
based “push-pull” fluorophores
Dmitry S. Kopchuk, Nikolay V. Chepchugov, Ekaterina S. Starnovskaya, Albert F.
Khasanov, Alexey P. Krinochkin, Sougata Santra, Grigory V. Zyryanov, Pralay Das,
Adinath Majee, Vladimir L. Rusinov, Valery N. Charushin
PII:
S0143-7208(18)31990-9
https://doi.org/10.1016/j.dyepig.2019.04.029
DYPI 7484
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 7 September 2018
Revised Date: 12 April 2019
Accepted Date: 12 April 2019
Please cite this article as: Kopchuk DS, Chepchugov NV, Starnovskaya ES, Khasanov AF, Krinochkin
AP, Santra S, Zyryanov GV, Das P, Majee A, Rusinov VL, Charushin VN, Synthesis and optical
properties of new 2-(5-arylpyridine-2-yl)-6-(het)arylquinoline-based “push-pull” fluorophores, Dyes and
Pigments (2019), doi: https://doi.org/10.1016/j.dyepig.2019.04.029.
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Synthesis and optical properties of new 2-(5-arylpyridine-2-yl)-6-
(het)arylquinoline-based “push-pull” fluorophores
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Dmitry S. Kopchuk,a,b Nikolay V. Chepchugov,a Ekaterina S. Starnovskaya,a,b Albert F.
Khasanov,a,b Alexey P. Krinochkin,a,b Sougata Santra*,a Grigory V. Zyryanov,a,b Pralay Das,c,d
Adinath Majee,e Vladimir L. Rusinov,a,b Valery N. Charushina,b
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a Department of Organic and Biomolecular Chemistry, Chemical Engineering Institute, Ural
Federal University, 19, Mira St., Yekaterinburg, 62000, Russian Federation.
*Email: sougatasantra85@gmail.com; ssantra@urfu.ru
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b I. Ya. Postovsky Institute of Organic Synthesis of RAS (Ural Division), 22/20, S.
Kovalevskoy/Akademicheskaya St., Yekaterinburg, 62099, Russian Federation
c Natural Product Chemistry and Process Development, CSIR-Institute of Himalayan Bioresource
Technology, Palampur-176061, HP, India
d Academy of Scientific & Innovative Research (AcSIR), New Delhi, India
e Department of Chemistry, Visva-Bharati (A Central University) Santiniketan-731235, India
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Dedicated to the 85-year anniversary of academician of the RAS Prof. Oleg N. Chupakhin
Abstract: 2-(5-Arylpyridine-2-yl)-6-(het)arylquinoline-based “push-pull” fluorophores were
synthesized by means of the heterocyclization reaction between the corresponding
isonitrosoacetophenone hydrazones and 6-bromoquinoline-2-carboxaldehyde followed by an aza-
Diels-Alder/Suzuki cross-coupling reaction sequence. The optical properties of the obtained
fluorophores were studied and the non-linear optic behavior for the two most representative ones
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were confirmed based on the solvatochromic experiments.
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Keywords: 2-(5-arylpyridine-2-yl)-6-(het)arylquinoline; “push-pull” fluorophores; “1,2,4-triazine
method”; optical properties; solvatochromic properties; data analysis
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1. Introduction
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The (benzo)bipyridine core is found in many natural compounds [1] and the 2,2’-
(benzo)bipyridines exhibit many properties and useful applications [2-6]. For instance, pyridine and
2,2′-(benzo)pyridine moieties are widely presented in anticancer drugs [7] such as streptonigrin,
streptonigrone and lavendamycin, in 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) and
cholesterol biosynthesis inhibitors [8], such as lovastatin, simvastatin [9] and cerivastatin which was
recently withdrawn from a market [10] (Fig. 1). Additionally, (iso)quinolone core itself is widely
presented in naturally occurring biologically-active compounds/drugs [11-13], for instance, those
possesing activity against malaria [14] or tuberculosis [15]. As benzo-derivatives of 2,2′-bipyridines
2-(2′-pyridyl)-quinolines are common ligands for the chelation of transition metals cations via
“classical” [16,17] or “rollover” cyclometallation [18], the “classical” cyclometallation is used for
the visual detection of some metal cations. For instance, very recently a reversible “turn off”
fluorescence response along with a visible color change of 2-pyridyl quinoline towards Cu2+ in semi-
aqueous conditions was reported [19]. Ruthenium(II) complexes of 2-(2′-pyridyl)-quinolines are
found in practical application as components for dye-sensitized solar cells [20], as catalysts for the
transfer hydrogenation of ketones [21] and, most importantly, as active water oxidation catalysts, to
aim their use as key components for devices designed to effect practical artificial photosynthesis
[22-30].
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Fig. 1. Most representative pyridines and 2,2′-benzobipyridines.
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The photophysical properties of 2-(2-pyridyl)-isoquinolines deserve special consideration,
since the annulation or addition of additional aromatic rings often leads to an improvement in the
photophysical characteristics of the compounds, namely, to the red shift of the absorption and
emission maxima compared with the parent 2,2'-bipyridines. In particular, such changes were
observed for 2-(5-arylpyridin-2-yl)-quinolines [31,32], as well as their 6,7-difluoro-containing
analogues [33]. On the other hand there are many reports dealing with 2,2′-bipyridines, including
their (het)aryl-substituted/annelated [34,35] or electronically congugated [36] derivatives as a new
class of “push-pull” fluorophores with prospective photophysical properties. We recently reported a
syntheis and the evaluation of photophysical proprties of new “push-pull” fluorophores based on
(het)aryl- or arylamino-substituted 2,2′-(aza)bipyridines [37,38].
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In the current manuscript we are pleased to report a convenient synthetic approach towards π-
extended derivatives of 2-(5-arylpyridin-2-yl)-quinolines, namely 2-(5-arylpyridine-2-yl)-6-
(het)arylquinoline as “push-pull” fluorophores and the study of their photophysical properties. The
previously reported “1,2,4-triazine methodology” [31-33] along with [39,40] Suzuki coupling was
used to prepare the target fluorophores.
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