Raman and infrared spectroscopy of molecular crystals

Barrow, R. F.; Long, D. A.; Sheridan, J.; Schräder, Bernhard

doi:10.1039/9781847556721-00235

Cited by 35 publications

(50 citation statements)

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“…However, since carboxylate group in bidentate bridging coordination behaves similar to a carboxylate free ion, 44 and since the latter exhibits a CO bonding intermediate between a pure single and double bond due to existence of the resonance hybrid structure, 45 theoretical k value was computed using the expression of force constant for multiple bond as k N ) k XY N(r 1 /r N ) where k XY is the force constant for a X-Y single bond, N is the bond order, and r 1 and r N are single and multiple bond lengths. 41 Taking N ) 1.5, r 1 ) 1.36 Å, and r N ) 1.27 Å, k Th came out to be 8.67 × 10 2 N/m. Comparing experimental values for COO (which are in good agreement with theoretical ones), we find that carboxylate group is similar in both samples.…”

Section: Molecular Conformation and Supramolecular Interactionsmentioning

confidence: 97%

“…40 The value of k was calculated from the empirical relation for an approximate force constant of a single bond between atoms X and Y as k XY ) 7.20 × 10 2 (Z X Z Y )(n X n Y ) -3 N/m, where Z and n are atomic number and principal quantum number of valence electrons, respectively. 41 The theoretical k value came out as 3.04 × 10 2 N/m. From the above two simultaneous equations, experimental values of k and R of CoStp-9 and CoStn-9 are determined (Table 4) The values are presented in Table 4.…”

Section: Molecular Conformation and Supramolecular Interactionsmentioning

confidence: 99%

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Chemistry at Air/Water Interface versus Reaction in a Flask: Tuning Molecular Conformation in Thin Films

et al. 2009

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Atomic force microscopy and X-ray reflectivity studies of cobalt stearate Langmuir-Blodgett (LB) films (CoStp) deposited from a preformed bulk sample on quartz substrates showed formation of a Volmer-Weber type monolayer but no multilayers as compared to the excellent multilayers of cobalt stearate films (CoStn) deposited at the air/water interface by the usual LB technique, in spite of both showing bidentate bridging type coordination of cobalt ions with the carboxylate group. The difference is attributed to existence of different headgroup conformers, observed from Fourier transform infrared (FTIR) studies. The CoStp films had a higher energy 'boat' conformation with linear O-Co-O linkage, whereas CoStn formed a low energy conformer with a bent O-Co-O configuration (bond angle of 105 degrees). Present results support the necessity of bidentate bridging coordination in multilayer deposition, but rejects its sufficiency by bringing out the crucial role played by air/water interface. Differences in surface pressure-molecular area isotherms and hydrocarbon tail-tail interactions (evident from FTIR spectra) of the films support the above statement. Methyl-methyl interactions observed in CoStn samples suggest hierarchy of supramolecular chemistry at the air/water interface in tuning the C-O-Co bond angle essential to satisfy the wetting condition with the substrate and subsequently form LB multilayers.

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Section: Molecular Conformation and Supramolecular Interactionsmentioning

confidence: 97%

Section: Molecular Conformation and Supramolecular Interactionsmentioning

confidence: 99%

Chemistry at Air/Water Interface versus Reaction in a Flask: Tuning Molecular Conformation in Thin Films

et al. 2009

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“…10 Lack of coincidence of Raman and IR bands in the spectra are typical of polyethylene-type compounds, where a local centre of symmetry exists in the middle of -CH 2 -CH 2 -groups, making the rule of mutual exclusion active. 23 The stretching vibrational modes of CH 2 and CH 3 groups occur in the region 2700-3600 cm 1 . In Fig.…”

Section: Outermost Wax Layermentioning

confidence: 99%

Raman spectroscopic study of the epicuticular wax layer of mature mango (Mangifera indica) fruit

Prinsloo

Plooy

Merwe

2004

J Raman Spectroscopy

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Little is known about the chemical composition of the natural wax layer covering mango (Mangifera indica) fruit. We report here on the role of Raman spectroscopy in a study that was undertaken to characterize the epicuticular wax of mature mango fruit. Scanning electron microscope measurements showed two morphologically distinct parts in the wax layer and Raman microscopy determined that they are chemically distinct. Crystalline aliphatic compounds protrude from an amorphous layer in which long-chain aliphatic, aromatic and unsaturated compounds are present. Raman spectra recorded on the perimeter of lenticels indicate an absence of the crystalline aliphatic compounds in this region and this information could assist in the solution of the problem faced by the mango industry of the discoloration around lenticels, which makes the fruit unacceptable as an export product. The results are supported by Fourier transform IR spectroscopy and both techniques are now employed as probes in a long-term project to study dynamic changes of the wax during fruit development and eventual processing, which includes the monitoring of possible changes in carotenoid content and the role of dust particles embedded in the wax.

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“…Despite the high spatial resolution and the high sensitivity of Raman spectroscopy [10,11] to detect different materials, to the author's knowledge, very little literature applying Raman spectroscopy to characterize interdiffusion in two-component injection molded parts is available [1,12]. Thus, this study focuses on the potential and limitations of Raman spectroscopy to detect interdiffusion.…”

Section: Introductionmentioning

confidence: 98%

Measurement of interdiffusion in polymeric materials by applying Raman spectroscopy

et al. 2015

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Raman and infrared spectroscopy of molecular crystals

Cited by 35 publications

References 0 publications

Chemistry at Air/Water Interface versus Reaction in a Flask: Tuning Molecular Conformation in Thin Films

Chemistry at Air/Water Interface versus Reaction in a Flask: Tuning Molecular Conformation in Thin Films

Raman spectroscopic study of the epicuticular wax layer of mature mango (Mangifera indica) fruit

Measurement of interdiffusion in polymeric materials by applying Raman spectroscopy

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