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Interference of H-bonding and substituent effects in nitro- and hydroxy-substituted salicylaldehydes.

ABSTRACT: Two intramolecular interactions, i.e., (1) hydrogen bond and (2) substituent effect, were analyzed and compared. For this purpose, the geometry of 4- and 5-X-substituted salicylaldehyde derivatives (X = NO(2), H or OH) was optimized by means of B3LYP/6-311 + G(d,p) and MP2/aug-cc-pVDZ methods. The results obtained allowed us to show that substituents (NO(2) or OH) in the para or meta position with respect to either OH or CHO in H-bonded systems interact more strongly than in the case of di-substituted species: 4- and 3-nitrophenol or 4- and 3-hydroxybenzaldehyde by ~31%. The substituent effect due to the intramolecular charge transfer from the para-counter substituent (NO(2)) to the proton-donating group (OH) is ~35% greater than for the interaction of para-OH with the proton-accepting group (CHO). The total energy of H-bonding for salicylaldehyde, and its derivatives, is composed of two contributions: ~80% from the energy of H-bond formation and ~20% from the energy associated with reorganization of the electron structure of the systems in question.

SUBMITTER: Jezierska-Mazzarello A

PROVIDER: S-EPMC3249548 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Interference of H-bonding and substituent effects in nitro- and hydroxy-substituted salicylaldehydes.

Jezierska-Mazzarello Aneta A Szatyłowicz Halina H Krygowski Tadeusz Marek TM

Journal of molecular modeling 20110427 1

Two intramolecular interactions, i.e., (1) hydrogen bond and (2) substituent effect, were analyzed and compared. For this purpose, the geometry of 4- and 5-X-substituted salicylaldehyde derivatives (X = NO(2), H or OH) was optimized by means of B3LYP/6-311 + G(d,p) and MP2/aug-cc-pVDZ methods. The results obtained allowed us to show that substituents (NO(2) or OH) in the para or meta position with respect to either OH or CHO in H-bonded systems interact more strongly than in the case of di-subst ...[more]

PMID: 21523547

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Project description:Styryl quinolines are biologically active compounds with properties largely depending on the substituents on the styryl and quinoline rings. The supramolecular aspects of this class of compounds are rarely explored. In this study, two new series of styryl quinoline derivatives, bearing -OH and -NO2 groups at the eighthposition of the quinoline ring and -SCH3, -OCH3, and -Br groups on the styryl ring, have been developed, and their structural, supramolecular, and cytotoxic properties have been analyzed. Crystallographic analyses revealed the exciting substituent-dependent structural and supramolecular features of these compounds. In general, the 8 -OH substituted derivatives (SA series) exhibited a non-planar molecular geometry having larger dihedral angles (5.75-59.3°) between the planes of the aromatic rings. At the same time, the 8 -NO2 substituted derivatives (SB series) exhibited a more or less planar molecular geometry, as revealed by the smaller dihedral angles (1.32-3.45°) between the aromatic rings. Multiple O-H···O, C-H···O, O-H···N, and π-π stacking interactions among the molecules lead to fascinating supramolecular architectures such as hydrogen-bonded triple helices, zig-zag 1D chains, π-π stacked infinite chains, and so forth in their crystal lattice. Hirshfeld surface analyses confirmed the existence of strong π-π stacking and other weak bonding interactions in these compounds. The preliminary cytotoxic properties of SA and SB series compounds were evaluated against the human cervical cancer cell lines (HeLa cells), which further highlighted the roles of functional substituents on the aromatic rings. The SA series compounds with the -OH substituent on the quinoline ring exhibited better cytotoxicity than the SB series compounds with a -NO2 substituent. Similarly, the electron-withdrawing group -Br on the styryl ring enhanced the cytotoxicity in both series. The IC50 values were 2.52-4.69 and 2.897-10.37 μM, respectively, for the SA and SB series compounds. Compound S3A having -OH and -Br groups on the quinoline and styryl ring, respectively, exhibited the best IC50 value of 2.52 μM among all the compounds tested. These findings confirm the relevance of the hydroxyl group in the eighth position of quinoline. In short, the present study attempts to provide a systematic analysis of the effects of aromatic ring substituents on the structural, supramolecular, and cytotoxic properties of styryl quinolines for the first time.

Dataset Information

Interference of H-bonding and substituent effects in nitro- and hydroxy-substituted salicylaldehydes.

Publications

Interference of H-bonding and substituent effects in nitro- and hydroxy-substituted salicylaldehydes.

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