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Rafał Topolnicki, University of Wrocław,
Elwira Borawska, University of Białystok
Dynamic properties of molecules study using inelastic incoherent neutron spectroscopy and
computational quantum chemistry methods
Frank Laboratory of Neutron Physics JINR Supervisor: Dorota Nowak, Ph.D. July 2011
Pentabromophenol
Uses:Chemical intermediate
Acta Crystallographica, Sec. E. Struct. Rep. Online 64 (2008) 1921
Molecular Formula
C6HBr
5O
Melting point 223-228 ºC
Boiling point 352 ºC
Water solubility Insoluble
Appearance Light brown powder
LD50
(rat) 200mg/kg
Pentachlorophenol
Acta Crystallographica 15 (1962) 1164
Pentachlorophenol is an organochlorine compound used as a pesticide and a disinfectant.
Molecular Formula
C6HCl
5O
Melting point 190-191 ºC
Boiling point 309-310 ºC
Water solubility 0.020 g/L at 30 °C
Appearance White crystalline solid
Time of flight
t – time of flightt0 – time when neutrons leavemoderatorL1 – path from reactor to sampleL2 – path from sample to detectorw – factor (scaling neutrons'energy to velocity)E0 – initial energyE1 – final energy
Application of IINS and QC calculations in studies of properties of selected lutidines, Sylwia Dobkowska, Katarzyna Kilan, Adam Kowalczyk, Kamil Kuźma
Types of internal vibration modes
In general for any molecule containing N atoms we have 3N-6 possible vibration modes (or 3N-5 for linear molecule like CO
2)
For each mode we can assign characteristic frequency.
Our goal is to connect frequencies visible on experimental spectrum with certain types of internal vibration in molecule
C-Br Bending C-ring Torsion C-Br Stretching
Calculated Intensiv ATOMS MODE
43.4 0.006 Br-C Out of plane48.6 0.002 Br-C Out of plane91.7 0.001 OH-C Out of plane
141.6 0.092 Br-C bending146.0 0.170 Br-C bending150.1 0.125 Br-C bending158.5 0.015 Br-C bending169.5 0.459 ring Out of plane210.8 0.049 Br-C stretching222.5 0.038 Br-C stretching237.3 0.000 Br-C stretching322.5 6.032 O-C bending332.6 2.198 ring Out of plane365.6 0.030 ring Out of plane387.2 1.042 C-O stretching459.7 90.984 O-H Out of plane557.4 25.326 ring torsion
Calculations
Obtain CIF file which contain informations about loactions of all atoms in molecule and molecules in Wigner–Seitz cell,
Build izolated molecule (or dimmer) and write positions of atoms in Z-matrix form,
Execute DFT calculation using Gaussian09 programme Choose B3LYP correlation-exchange potential, Select proper functional base - 6-31G* Optimalize atoms placements, Calculate vibrations
Analysis and visualization of resultsAll calculations were preformed in ICM in Warsaw
318,78 cm-1
O-H Out of Plane
316,26 cm-1
365,94 cm-1
O-H Out of Plane in both molecues
474,01 cm-1
CC ring deformation
Pentabromophenol
318,78 cm -1
1088,11 cm -1
33,26 cm -1
275,41 cm -1
Dynamika molekularna kryształów z rodziny polifenyli, J. W. Wąsicki, Wydawnictwa UAM, 1991 Molecular dynamics of eithisterone studied by 1H NMR, IINS and quantum mechanical calculations, Chemical Physics 317 (2005) 178-187 Fizyka chemiczna, J. M. Janik, PWN 1989
References
Thank you for your attention!
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