Natural monoacetylenes studied by quantum-chemical chemistry

Journal of Spectroscopy, Mar 2019

This study is a part of the project focused on the vibrational analysis of natural mono- and polyacetylenes by using Raman spectroscopy and theoretical calculations. Their vibrational spectra show strong and polarized –C≡C– bands in the region of about 2200 cm–1. Mono- as well as polyacetylenes are supposed to be active in plants yet not available in an isolated form, so theoretical simulation of their vibrational spectra and comparison with the registered ones seems to be an excellent way to confirm or exclude the presence of these compounds in the investigated plants. Such an approach was applied here to analyze polyacetylenes in roots of Coreopsis grandiflora. According to literature, this plant should contain a monoacetylene substituted by a thiophene ring. Theoretical calculations allowed to confirm this assumption.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://downloads.hindawi.com/journals/jspec/2010/362967.pdf

Natural monoacetylenes studied by quantum-chemical chemistry

Spectroscopy Natural monoacetylenes studied by quantum-chemical chemistry Maciej Roman 0 Malgorzata Baranska 0 0 Faculty of Chemistry, Jagiellonian University , Krakow , Poland This study is a part of the project focused on the vibrational analysis of natural mono- and polyacetylenes by using Raman spectroscopy and theoretical calculations. Their vibrational spectra show strong and polarized -C?C- bands in the region of about 2200 cm?1. Mono- as well as polyacetylenes are supposed to be active in plants yet not available in an isolated form, so theoretical simulation of their vibrational spectra and comparison with the registered ones seems to be an excellent way to confirm or exclude the presence of these compounds in the investigated plants. Such an approach was applied here to analyze polyacetylenes in roots of Coreopsis grandiflora. According to literature, this plant should contain a monoacetylene substituted by a thiophene ring. Theoretical calculations allowed to confirm this assumption. Mono- and polyacetylenes; DFT; Raman spectroscopy 1. Introduction 2. Computational methods All calculations were carried out using the Gaussian?03 package of programs [ 4 ]. Geometries and vibrational frequencies of model compounds were calculated by means of DFT method with B3LYP functional [ 2,6 ] and the aug-cc-pVDZ basis set [3]. All frequencies were scaled by 0.96 scaling factor. 3. Results and discussion Monoacetylenes occurring in roots of Coreopsis grandiflora are supposed to be biological active, but are not available in an isolated form. Raman spectrum obtained from the roots shows characteristic band at 2194 cm?1 [ 7 ]. According to Bohlmann [ 8 ], this plant should contain a monoacetylene substituted by a thiophene ring. To verify this assumption theoretical calculations of three model monoacetylenes were performed (Fig. 1). The compounds were optimized and their Raman spectra were simulated. Table 1 contains selected geometrical parameters of three studied models while the most characteristic frequencies together with their assignment are gathered in Table 2. The first analyzed monoacetylene is substituted only by a thiophene (MA-Th). For this compound theoretical calculations show very strong band due to ?C?C? stretching mode at 2111 cm?1. The second monoacetylene considered in this work consists of an acetylene with a thiophene ring and a vinyl group (V-MA-Th). Raman spectrum predicted for this compound gives very strong band due to ?C?C? stretching mode at 2194 cm?1. The most expanded monoacetylene modeled here is built of a thiophene ring, a vinyl and an alkyl groups (Al-V-MA-Th). Similarly to previous compound theoretical calculations show very strong band due to ?C?C? stretching mode at 2194 cm?1. All reported here frequencies of ?C?C? vibration were scaled as reported in computational part. The obtained results shows that substitution of the monoacetyle with a vinyl group and thiophene ring leads to a good agreement between theoretical and experimental data. Further extension of the substituents does not affect the frequency of ?C?C? vibrational mode since they are too far from the triple bond. So, the most significant are the closest neighbors of the ?C?C? system. The presence of additional substituents has no influence on the position of this band. Based on calculations it was possible to exclude from the consideration MA-Th since its Raman signal is moved about 80 cm?1 in comparison to experimental data. Raman band at 2194 cm?1 present in the spectrum of Coreopsis grandiflora roots was predicted also for two investigated model compounds (V-MA-Th and Al-V-MA-Th). So we can conclude that this plant probably contain a monoacetylene substituted by two groups and one of them is a thiophene ring. Generally, theoretical calculations allowed to confirm the assumption found in the literature. 4. Conclusions Due to the lack of monoacetylenes in an isolated form theoretical calculations can be very useful in order to identify these compound in the plant tissues. They give possibilities to predict vibrational spectra, which can be compared directly with the experimental data. Theoretical calculations can be used to built a spectral libraries of essential compounds not available in an isolated form, but which are important for agriculture, ecology or pharmaceutical industry. The most characteristic frequencies (in cm?1) together with their assignment for three model monoacetylenes Acknowledgements V-MA-Th 671 813 905 1161 1414 1495 1593 2194 ? Al-V-MA-Th 666 815 930 1162 1414 1495 1621 2194 ? Band assignment ?(C?H) in ring ?(C?S) ?(=C?H) in side-chain ?(C=C) and ?(C?H) in ring ?(C=C) and ?(C?C) in ring ?(C=C) in ring ?(C=C) in side-chain ?(C?C) ?(?C?H) The authors thank for the computing time to the Academic Computer Centre ?Cyfronet?, Krak?w, Poland. This research was supported by the Ministry of Science and Higher Education (MNiSW, Grant No. N204013635, 2008?2011). International Journal of Medicinal Chemistry Hindawi Publishing Corporation ht p:/ www.hindawi.com International Hindawi Publishing Corporation ht p:/ www.hindawi.com International Journal of Photoenergy International Journal of Analytical Chemistry Advances in Physical Chemistry Hindawi Publishing Corporation Hindawi Publishing Corporation ht p:/ www.hindawi.com International Journal of Carbohydrate Chemistry Hindawi Publishing Corporation ht p:/ www.hindawi.com The Scientiifc World Journal Hindawi Publishing Corporation ht p:/ www.hindawi.com Submit your manuscr ipts Journal of Spectroscopy Hindawi Publishing Corporation ht p:/ www.hindawi.com International Journal of Inorganic Chemistry Journal of Applied Chemistry organic Hindawi Publishing Corporation ht p:/ www.hindawi.com Theoretical Chemistry Chromato graphy Research International Journal of [1] M. Baranska and H. Schulz , Spatial tissue distribution of polyacetylenes in carrot root , Analyst 130 ( 2005 ), 855 - 859 . [2] A.D. Becke , Density-functional thermochemistry . III. The role of exact exchange , J. Chem. Phys . 98 ( 1993 ), 5648 - 5652 . [3] T.H. Dunning Jr ., Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , J. Chem. Phys . 90 ( 1989 ), 1007 - 1023 . [4] M.J. Frisch , G.W. Trucks , H.B. Schlegel , G.E. Scuseria , M.A. Robb , J.R. Cheeseman , J.A. Montgomery Jr ., T. Vreven , K.N. Kudin , J.C. Burant , J.M. Millam , S.S. Iyengar , J. Tomasi , V. Barone , B. Mennucci , M. Cossi , G. Scalmani, N. Rega , G.A. Petersson , H. Nakatsuji , M. Hada , M. Ehara , K. Toyota , R. Fukuda , J. Hasegawa , M. Ishida , T. Nakajima , Y. Honda , O. Kitao , H. Nakai , M. Klene , X. Li , J.E. Knox , H.P. Hratchian , J.B. Cross , V. Bakken , C. Adamo , J. Jaramillo , R. Gomperts , R.E. Stratmann , O. Yazyev , A.J. Austin , R. Cammi , C. Pomelli , J.W. Ochterski , P.Y. Ayala , K. Morokuma , G.A. Voth , P. Salvador , J.J. Dannenberg , V.G. Zakrzewski , S. Dapprich , A.D. Daniels , M.C. Strain , O. Farkas , D.K. Malick , A.D. Rabuck , K. Raghavachari , J.B. Foresman , J.V. Ortiz , Q. Cui , A.G. Baboul , S. Clifford , J. Cioslowski , B.B. Stefanov , G. Liu, A. Liashenko , P. Piskorz , I. Komaromi , R.L. Martin , D.J. Fox , T. Keith , M.A. Al-Laham , C.Y. Peng , A. Nanayakkara , M. Challacombe , P.M.W. Gill , B. Johnson , W. Chen, M.W. Wong , C. Gonzalez and J.A. Pople , Gaussian 03, Revision E. 01, Gaussian , Inc., Wallingford, CT , 2004 . [5] S.L. Hansen , S. Purup and L.P. Christensen , Bioactivity of falcarinol and the influence of processing and storage on its content in carrots (Daucus carota L .), J. Sci. Food Agric . 83 ( 2003 ), 1010 - 1017 . [6] C.T. Lee , W.T. Yang and R.G. Parr , Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density , Phys. Rev. B 37 ( 1988 ), 785 - 789 . [7] B. Schrader , H. Schulz , M. Baranska , G.N. Andreev , C. Lehner and J. Sawatzki , Non-destructive Raman analyses - polyacetylenes in plants , Spectrochim. Acta A 61 ( 2005 ), 1395 - 1401 . [8] E. Winterfeld , Ferdinand Bohlmann ( 1921 -1991) und sein wissenschafliches Werk , Liebigs Ann. Chem . ( 1994 ), I-XXXIV.


This is a preview of a remote PDF: http://downloads.hindawi.com/journals/jspec/2010/362967.pdf

Maciej Roman, Malgorzata Baranska. Natural monoacetylenes studied by quantum-chemical chemistry, Journal of Spectroscopy, DOI: 10.3233/SPE-2010-0453