The synthesis of highly fluorescent heterocyclic compounds: Pyrido[2′,1′:2,3]imidazo[4,5-b]quinoline-12-yl cyanides

Synthesis of new fluorescent compounds from 5-nitro-1H-indazole

“…The new 3-alkyl-3H-pyrazolo[4,3-a]acridin-11-carbonitrile 3a-d were synthesized via the nucleophilic substitution of hydrogen of 1-alkyl-1H-indazole 1a, b with arylacetonitriles 2a, b in basic MeOH solution and then intramolecular electrophilic aromatic substitution in moderate yields 16,[17][18][19][20][21][22] (Scheme 1). When R' is an electron withdrawing group such as NO2 group, the yield of the reaction is very low, since the corresponding conjugated base is a weak nucleophile.…”

“…[8][9][10] Fluorescent heterocyclic compounds are of interest as functional materials in many disciplines such as emitters for electroluminescence devices, 11 molecular probes for biochemical research, 12 in traditional textile and polymer fields, 13 whitening agents 14 and photo conducting materials. 15 We have previously described a process for the relatively feasible production of some new fluorescent compounds 16,17 by reacting the imidazo[1,2-a]pyridine with arylacetonitriles via nucleophilic substitution of hydrogen. [18][19][20][21] Now we describe here the syntheses of new fluorescent heterocyclic compounds from nitro derivatives of indazole by this method and evaluation of their spectroscopic properties.…”

Synthesis, spectroscopic characterization and DFT calculations of a new highly fluorescent heterocyclic system: imidazo[4,5-a]quinindoline

“…[17][18][19][20][21][22] In Scheme 3 neutral and some charge-separated mesomeric structures of 3a-d are presented. As seen in this scheme, there are two nitrogen donors which can explain the shoulder on the right side of the peaks in emission spectra of compounds 3a-d (Figure 3).…”

“…In the following mechanism [17][18][19][20][21][22][23] the ring closure proceeds via an electrocyclic pathway, wherein intermediate B is converted into C followed by loss of one H 2 O molecule, whereupon compounds 3a-d are obtained (Scheme 2).…”

“…Based on these aspects and in continuation with our research work on the efficient synthesis of new dyes and fluorescent nitrogen heterocyclic compounds, [17][18][19][20][21][22][23] we examined the transformation of 1-alkyl-5-nitro-1H-benzoimidazole with 2-(1-alkyl-1H-3-indolyl)acetonitrile to new fluorescent heterocyclic system imidazo [4,5-a]quinindoline via the nucleophilic substitution of hydrogen. 24,25 The fluorescence properties of these new heterocyclic compounds and DFT calculations of one structure by using the B3LYP hybrid functional and the 6-311+G(d,p) basis set have also been studied.…”