Crystal structure, spectroscopic, and theoretical studies of 2-methylamino-6-methyl-4 nitropyridine N-oxide

Wiśniewski, Łukasz; Urbanowicz, Agnieszka; Jerzykiewicz, Lucjan B.; Makarewicz, A.; Deperasińska, Irena; Zwan, Gert van der; Haraszkiewicz, Natalia; Puszko, Aniela; Szemik-Hojniak, Anna

doi:10.1016/j.molstruc.2008.10.029

Cited by 6 publications

(28 citation statements)

References 23 publications

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“…This produces a structure very different from that of 2B6M, in which the crystal is composed of dimers linked by the bifurcated four-center internal hydrogen bonds. 18 In 2B5M, the intramolecular N-HÁ Á ÁO [2.572(3) Å ] hydrogen bond is weaker than that in 2M6M [2.563(3) Å ], 23 and in 2B6M [2.556 (2) Å ]. 18 The distance between the parallel planes of monomers in a double layer of hydrogen-bonded polymers of 2B5M is slightly larger [3.055(4) Å ] than that in 2B6M [3.049(3) Å ), 18 but may still be a source of stacking and excitonic interactions that appear in the form of band splitting in the absorption spectrum of 2B5M in nonpolar solvents.…”

Section: Experimental Section Materials and Instrumentationmentioning

confidence: 99%

“…1) with the alkylamino (NHR) group occupying the ortho-position and the nitro group in the para-position with respect to the NO group has been undertaken. [17][18][19][20][21][22][23][24] In these molecules, since all electron-and proton-donor and -acceptor participants are commonly present in the same molecule, proton-coupled-electron-transfer (PCET) reactions, which are of biological importance, may take place. [25][26][27][28][29] In electron-transfer reactions, the >NO and the alkylamino group (ÀNHR, where the R substituent may be methyl, ethyl or butyl) act as electron donors while the nitro group (NO 2 ) and the pyridine ring are electron acceptors.…”

Section: Introductionmentioning

confidence: 99%

“…17,19,24 A dual emission band observed in n-octane includes the most intense band of the normal (N*) form (B470 nm) and a significantly weaker red-shifted PT* band (545 nm). 23 The latter results from the intramolecular excited-state proton transfer (ESIPT) within the internal (N-H. . .O) hydrogen bridge.…”

Section: Introductionmentioning

confidence: 99%

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The impact of solvent polarity on intramolecular proton and electron transfer in 2-alkylamino-4-nitro-5-methyl pyridine N-oxides

Szemik-Hojniak

Wiśniewski

Deperasińska

et al. 2012

Phys. Chem. Chem. Phys.

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The crystal structure of 2-butylamino-4-nitro-5-methyl pyridine N-oxide (2B5M) and solution studies of both 2B5M and 2-methylamino-4-nitro-5-methyl pyridine (2M5M) N-oxide are presented. Steady-state absorption and emission measurements were employed for both molecules while a picosecond fluorescence up-conversion technique was used to follow the dynamic behavior of the 2M5M system. The experimental methods were complemented by DFT and TD DFT B3LYP/6-31G(d,p) calculations involving ground and excited-state optimization which in the case of the smaller 2M5M molecule were extended to the CAM-B3LYP/6-31G(d,p) method. The solvent effect is incorporated by applying the polarizable continuum (PCM) model. The data reveal that the 2B5M molecule crystallizes in the monoclinic space group P2(1)/c and its crystal lattice is composed of monomers with intramolecular N-H···O [2.572(3) Å] hydrogen bonds, connected into a polymer network by weak intermolecular C-H…O [3.2-3.4 Å]-type interactions. Quantum-chemical calculations show that the aminoalkyl substitutent in aminoalkyl-pyridine N-oxides is a specific determinant of the CT nature of the lowest-lying excited electronic ππ* state, distinguishing them from other nitroaromatic compounds. The results of both picosecond fluorescence up-conversion experiments in different solvents and quantum-chemical calculations suggest that in nonpolar media the ESIPT process in 2M5M is favored, while in polar acetonitrile, the N* → PT* transition demands barrier-crossing and thus unfavorable thermodynamic conditions do not allow the ESIPT to occur. The signals of picosecond fluorescence up-conversion of 2M5M are solvent- and emission-wavelength dependent. The three time components found in a weakly polar isooctane-dioxane mixture have been attributed to solvation dynamics (∼500 fs), and to relaxation of N* and PT* forms while in acetonitrile, a very rapid fluorescence decay with a time constant (2.3-4.0 ps) indicative of the presence of the normal (N*) form was observed. Much shorter fluorescence lifetimes in alcohols (a few picoseconds) and in D(2)O (less than 200 fs) than in aprotic solvents suggest that in protic media, the solvent molecules participate in the ESIPT, bridging between the methylamine group and the N-oxide group of 2M5M.

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Section: Experimental Section Materials and Instrumentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The impact of solvent polarity on intramolecular proton and electron transfer in 2-alkylamino-4-nitro-5-methyl pyridine N-oxides

Szemik-Hojniak

Wiśniewski

Deperasińska

et al. 2012

Phys. Chem. Chem. Phys.

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“…Temperature effects were useful in evidencing the presence of excited-state H-bonds. Two kinds of experiment are reported in the literature data: measurements in an interval of temperatures around room temperature [36,115,134,[144][145][146][147] and measurements in glassy solutions at 77 K [29,83,120,148].…”

Section: Other Experimental Parameters (Temperature Excitation Wavelmentioning

confidence: 99%

“…The measurements of fluorescence lifetimes at variable temperatures in short interval ranges around 298 K in protic solvents was used to differentiate between some possible mechanisms such as electron ejection [89], participation of TICT states in the deactivation pathway, flip-flap motion of the amine group in non-polar and polar solvents, 1-N-methylamino-and 1-N,N-dimethylamino-9,10-anthraquinone dyes and coumarin [36,115,144,145], the ESIPT mechanism [146], etc. Experimental determinations were also used for estimation of the activation energy of the various processes and for estimation of the rotational diffusion time [147].…”

Section: Other Experimental Parameters (Temperature Excitation Wavelmentioning

confidence: 99%

Solute–Solvent Hydrogen Bond Formation in the Excited State. Experimental and Theoretical Evidence

Matei

Ionescu

Hillebrand

2010

Hydrogen Bonding and Transfer in the Excited State

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Hydrogen bonds (H-bonds) are of great importance in biological systems, as they are responsible for the secondary structure of proteins and nucleic acids and are also involved in the mechanisms of enzyme catalysis. Supramolecular chemistry makes use of H-bonds in building up novel compounds of various architectures.The identification of these interactions and the analysis of their influence on the photophysical properties are also important in designing new fluorophores for different applications, the processes involved being rather complex in nature and often only partially understood.The main feature reflecting H-bond interaction in both the ground and excited states is the solvatochromic effect on the absorption and fluorescence spectra. This implies that changes in the solvent nature or composition produce shifts in the position, shape and intensity of the spectral bands. The source of solvatochromic shifts is the different solvation of the ground and excited states: depending on the relative stabilization of these states by solvents, bathochromic (positive)or hypsochromic (negative)shifts of the maximum of the band can be observed experimentally. Thus, such changes are indicative of the interactions occurring between the solute and the solvent in its immediate vicinity. The solute-solvent interactions are classified into:1. non-specific interactions caused by polarity/polarizability effects; 2. specific interactions, such as H-bonds.

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Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide – Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

Bryndal

Lorenc

Macalik

et al. 2019

Journal of Molecular Structure

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publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.Crystal structure, vibrational and optic properties of 2-Nmethylamino-3-methylpyridine N-oxide e Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations Synthesis Crystal structure IR Raman UVeVis and luminescence spectra NBO and DFT calculations a b s t r a c tThe crystal and molecular structure and physicochemical properties of 2-N-methylamino-3methylpyridine N-oxide (MA3MPO) have been studied. MA3MPO was synthesized from 2-amino-3methylpyridine by several steps to form colorless crystals suitable for crystallographic analysis. The data reveal that MA3MPO crystallizes in the monoclinic space group P2 1 /n. The studied compound contains a nearly flat triply substituted pyridine skeleton whose structure is stabilized by an intramolecular NeH,,,O hydrogen bond. The N-oxide molecules are connected together by weak CeH/O hydrogen bonds, an acceptor of which is the oxygen atom from the N-oxide group. This leads to creation of two-dimensional network of hydrogen bonds. Its IR, Raman, UVeVis and luminescence spectra have been measured and analyzed on the basis of DFT and NBO quantum chemical calculations in which the B3LYP/6-311þþG(d,p) approach was applied. The distribution of the electron levels in the studied compound has been analyzed in terms of the possibility of its participation in the ligand-to-lanthanide ion energy transfer.

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Crystal structure, spectroscopic, and theoretical studies of 2-methylamino-6-methyl-4 nitropyridine N-oxide

Cited by 6 publications

References 23 publications

The impact of solvent polarity on intramolecular proton and electron transfer in 2-alkylamino-4-nitro-5-methyl pyridine N-oxides

The impact of solvent polarity on intramolecular proton and electron transfer in 2-alkylamino-4-nitro-5-methyl pyridine N-oxides

Solute–Solvent Hydrogen Bond Formation in the Excited State. Experimental and Theoretical Evidence

Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide – Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

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