Density functional study of a model amide. Prediction of formamide geometry, dipole moment, IR harmonic vibration ν CO and GIAO NMR shieldings

Kupka, Teobald; Gerothanassis, Ioannis P.; Demetropoulos, Ioannis N.

doi:10.1016/s0166-1280(00)00441-3

Cited by 31 publications

(20 citation statements)

References 58 publications

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“…For example, using DFT and MP2 methodology combined with basis sets containing (or lacking) polarization and diffuse functions [73], we also noticed the impact of a basis set on the predicted planarity/pyramidalization of NH 2 group in free formamide molecule. It is apparent in the current study from Table 1 that, in contrast to B3LYP, the M06-2X calculations with basis sets containing polarization and diffuse functions are capable of predicting a nonplanar structure of the ZnPc complex in a polar environment.…”

Section: Resultsmentioning

confidence: 87%

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

2017

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A theoretical investigation on the planarity of molecular structure of zinc phthalocyanine (ZnPc) and its aromaticity has been performed using B3LYP and M06-2X density functionals combined with selected Pople-type basis sets. The effect of the applied calculation method on the optimized structure of ZnPc and ZnPc•••H 2 O, both in the gas phase and in the polar solvent, was analyzed. To quantify the aromaticity of the ZnPc and ZnPc•••H 2 O complexes, both the geometric and magnetic criteria, i.e., Harmonic Oscillator Model of Aromaticity (HOMA) index and the nucleus-independent chemical shift (NICS) values at the centers or 1 Å above the centers of structural subunits, were calculated. The energies of highest energy occupied molecular orbital (HOMO) and lowest energy unoccupied molecular orbital (LUMO) and energy gaps were also estimated. The results show that the free ZnPC molecule is flat in the gas phase and nonplanar in the polar environments (DMSO and water). ZnPC•••H 2 O is nonpolar in the gas phase and polar solvent which is in agreement with recent X-ray reports. Both HOMA and NICS indexes indicate the presence of highly aromatic macrocycle and benzene rings while these parameters for pyrrolic ring are significantly smaller than in free pyrrole. The presence of polar solvents practically does not change aromaticity of the ring subunits of the studied compounds.

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Section: Resultsmentioning

confidence: 87%

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

2017

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“…As we have used the gaseous geometry of formamide this disagreement may originate from the possible existence of nonplanar conformation. The pyramidal arrangement of NH 2 group has been the subject of theoretical 71, 72 and experimental 73 debates but the nonplanar arrangement has not been excluded. The HTCH/B3LYP and B97–1 functionals produce values about 4.3–4.6%/7.8% and 7.4% higher than experiment, while the MP2, CCSD and CCSD(T) schemes give dipole moments that are about 5.2, 7.6, and 6.0% larger.…”

Section: Resultsmentioning

confidence: 99%

Electric properties of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide—Post‐HF and DFT study

Benková

Černušák

Zahradnı́k

2007

Int J of Quantum Chemistry

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Dipole moments , static electric polarizabilities ␣, and hyperpolarizabilities ␤ of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide have been evaluated in the DFT and post-HF approximations. Within the DFT, the family of HCTH and hybrid functionals (B3LYP, B97-1) have been adopted. The qualitative and quantitative performance of both functional types have been examined by confrontation with the CCSD(T) method. The DFT model appears to be adequate for dipole moments and polarizabilities, while the hyperpolarizabilities are exaggerated, especially ␤ yyy (too negative) and ␤ zzz (too positive) components. The replacement of oxygen by sulfur reduces the DFT hyperpolarizability, which contradicts an increase predicted with the post-HF approach. HCTH dipole moments in majority of cases are in better agreement with the CCSD(T) estimates than are the hybrid functionals. On the other hand, the hybrid functionals perform slightly better for polarizability and hyperpolarizability evaluations. The effects of basis set size with augcc-pVXZ (X ϭ D, T, Q) on the electric properties have also been studied. The sensitivity of the electric properties to the basis set effects increases from the dipole moment to the hyperpolarizability. The axial ␣ zz and ␤ zzz components display smaller sensitivity to the basis set extension. The carbonyl/thiocarbonyl containing molecules are characterized by negative/positive sign of hyperpolarizability vector projection into the dipole moment direction.

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“…It is worth mentioning here that in the literature, several examples are found for variation of dipole moments from the experimental results depending on the quantum chemical method used. It is stated [62], "it should be stressed that the RHF values are better than the MP2 ones but worse than the corresponding DFT results." It is also observed that dipole moment value in 6-31G basis set is overestimated for several systems [63].…”

Section: Estimation Of Dipole Moment Experimentally and Theoreticallymentioning

confidence: 95%

Experimental and theoretical study: Determination of dipole moment of synthesized coumarin–triazole derivatives and application as turn off fluorescence sensor: High sensitivity for iron(III) ions

Joshi

Kumari

Bhattacharjee

et al. 2015

Sensors and Actuators B: Chemical

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Density functional study of a model amide. Prediction of formamide geometry, dipole moment, IR harmonic vibration ν CO and GIAO NMR shieldings

Cited by 31 publications

References 58 publications

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Solvent impact on the planarity and aromaticity of free and monohydrated zinc phthalocyanine: a theoretical study

Electric properties of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide—Post‐HF and DFT study

Experimental and theoretical study: Determination of dipole moment of synthesized coumarin–triazole derivatives and application as turn off fluorescence sensor: High sensitivity for iron(III) ions

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