Supramolecular structure of phellopterin isolated from the roots of heracleum thomsoni: A furanocoumarin

Transcription

1 Indian Journal of Pure & Applied Physics Vol. 53, December 2015, pp Supramolecular structure of phellopterin isolated from the roots of heracleum thomsoni: A furanocoumarin Bandhan Sharma* Department of Physics, Govt College for Women Parade (Affiliated to University of Jammu), Jammu * bandhansharma79@yahoo.com Received 16 September 2014; revised 14 May 2015; accepted 21 August 2015 The crystal structure of phellopterin has been determined by X-ray diffraction method. The compound crystallizes in the triclinic space group P1 with unit cell parameters: a = 8.431(3) Å, b = 8.947(3) Å, c = (4) Å, = 69.11(5), = 71.13(5)º and = 78.04(5) º, Z = 2, V=737.9(4) Å 3. The structure has been solved by direct methods and refined to reliability index of The molecules of phellopterin are linked by paired C-H...O hydrogen bond. The face to face... stacking interactions link the planar tricyclic moiety with one another and pack in parallel arrangements. Keywords: Furanocoumarins, Supramolecular, X-ray diffraction, Pyrone ring, Hydrogen bonding 1 Introduction The photochemical behaviour in furanocoumarins is, generally, attributed to the carbonyl stretching (C=O) in the pyrone moiety of coumarin nucleus 1. Phellopterin is a furanocoumarin which strongly inhibits the binding of 3H-diazepam to central nervous system benzodiazepine receptor in vitro 2. The inhibitory activity of phellopterin is due to competitive inhibition of the benzodiazepine ligand binding suggesting that phellopterin is a partial agonist of the central benzodiazepine receptors in vitro 3. Some furanocoumarin such as bergapten, xanthotoxin, impertorin and phellopterin activates adrenalin-induced lipolysis. Phellopterin also activates ACTH-induced lipolysis 4. The chemical structure of phellopterin is shown in Fig Experimental Details The title compound has been isolated from the fruits of phellopterus littoralis 5. Later it has been reported to occur in several other plants of the umbelliferae and rutaceae families. In the present study, it has been isolated from the roots of heracleum thomsoni from Leh and Ladakh region of Jammu and Kashmir State of India 6. A transparent needle shaped single crystal of the title compound with dimensions ( )mm was mounted on the Enraf-Nonius CAD-4 diffractometer for automatic intensity data collection by using MoK radiation ( = Å). /2 scan mode was employed for the data collection with -range º. The compound crystallizes in the triclinic space group P1 with unit cell parameters: a=8.431(3) Å, b=8.947(3) Å, c=11.125(4) Å, =69.11(5)º, =71.13(5)º and =78.04(5)º, Z=2, V=737.9(4) Å 3. A total of 6087 reflections were recorded and out of which 2586 were found to be unique ( 10 h 11, 11 k 11, 14 l 14), 2549 were considered to be observed [Fo>4σ(Fo)]. The reflection data were collected for Lorentz and polarization effects and no absorption correction was applied. The structure was determined by SHELXS97 Software 7. Full matrix least square refinement of all non-hydrogen atoms including their corresponding thermal parameters was carried out using SHELXL97 software 8. The final cycle of refinement with anisotropic thermal parameters for non-hydrogen atoms converged R-factor at Atomic scattering Fig. 1 Chemical structure of phellopterin

2 SHARMA: SUPRAMOLECULAR STRUCTURE OF PHELLOPTERIN 809 Table 1 Crystal data structure refinement details Crystal description Transparent needles Emperical formula C17H16O5 Formula weight Crystal size mm Temperature 293(2) K Wavelength Å Unit cell dimensions a=8.431(3) Å, b=8.947(3) Å, c=11.125(4) Å, =69.11(5)º, =71.13(5)º and =78.04(5)º Volume 737.9(4) Å 3 Crystal system triclinic Spacegroup P1 Z, Calculated density 2, Mg/m 3 F(000) 316 -range for data 2.04 to º collection Scan mode /2 Index range -10 h 11, -11 k11, -14 l 14 No. of reflections collected 6087 Unique reflections 2586 Observed reflections 2549 Refinement method Full-matrix least-squares on F 2 Data/restraints/parameters 2586/0/203 Goodness-of-fit on F Final R indices R 1 = , wr 2 = R indices (all data) R 1 = , wr 2 = Largest diff. Peak and hole and e Å 3 factor were taken from International Tables for Crystallography (1992, Vol. C Tables and ). The crystallographic data are listed in Table 1. 3 Results and Discussion The bond distances and bond angles are presented in Table 2. An ORTEP view of the molecule with atomic numbering scheme 9 is in Fig. 2. The geometrical calculations were performed by using PARST 10 and PLATON 11. The bond distances and angles are in good agreement with the values reported for some analogous structures The magnitude of torsion angle C9-O17-C18-C19 present in the pre-nyloxy side chain located at atom C9 is 174.3(2)º which is 176.9(2)º (molecule-i) and 62.2(2)º (molecule-ii) in case of imperoterin. However, this value is in good agreement with the corresponding values reported for related furanocoumarins The molecules of phellopterin are linked by paired C-H...O hydrogen bonds into C(6) graph set, where C refers to chain 17. The molecules are linked to one Table 2 Bond distances (Å) and bond angles (º) for non-hydrogen atoms (esd s in parentheses) O1-C (2) O8-C (2) O1-C (2) C9-O (2) C2-C (2) C9-C (2) C3-C (2) C9-C (2) C4-O (2) C10-C (2) C4-C (2) C12-C (2) C4-C (2) O15-C (2) C5-C (3) O17-C (3) C5-C (2) C18-C (3) C6-C (3) C19-C (3) C7-O (3) C20-C (3) C7-O (2) C20-C (4) C10-O1-C (2) C9-C10-C (2) C3-C2-O (2) C4-C11-C (2) C2-C3-C (2) C4-C11-C (2) O15-C4-C (2) C10-C11-C (2) O15-C4-C (2) C13-C12-C (2) C11-C4-C (2) C13-C12-C (2) C6-C5-C (2) C4-C12-C (2) C5-C6-C (2) O8-C13-C (2) O14-C7-O (2) O8-C13-C (2) O14-C7-C (2) C9-C13-C (2) O8-C7-C (2) C4-O15-C (2) C13-O8-C (2) C9-O17-C (2) O17-C9-C (2) O17-C18-C (2) O17-C9-C (2) C20-C19-C (3) C13-C9-C (2) C19-C20-C (3) O1-C10-C (2) C19-C20-C (2) O1-C10-C (2) C21-C20-C (2) Table 3 Geometry of C-H...O hydrogen bonds C-H...O H...O(Å) C...O(Å) C-H...O(º) C2-H2...O C5-H5...O another through C-H...O hydrogen bonds and hydrogen-bonding network is shown in Fig. 3. The C2-H2...O14 and C5-H5...O1 intermolecular hydrogen interactions result into a linear chain like configuration. In intermolecular C2-H2...O14 interaction, C2 at (x, y, z) acts as hydrogen donor to O14 at ( 1+x, 1+y, z) where as in case of C5-H5...O1 intermolecular interactions, O1 at (1+x, y, z) acts as hydrogen acceptor. The C-H...O linear chains packed along bc-plane over different layers of molecule depicts the supramolecular structure of phellopterin. The geometry of C-H...O hydrogen bonds is presented in Table 3.

3 810 INDIAN J PURE & APPL PHYS, VOL 53, DECEMBER 2015 Fig. 2 ORTEP view of the molecule with displacement ellipsoids drawn at the 50% probability level Fig. 3 C-H...O hydrogen-bonding network

4 SHARMA: SUPRAMOLECULAR STRUCTURE OF PHELLOPTERIN 811 Fig. 4 Intermolecular C-H... stacking interactions The bifurcated H22B has two intermolecular interactions with 1 and 2 at (1 x, 1 y, 1 z) which is responsible for mutual intermolecular interactions between the molecules. This type of edge-to-face...h interactions also supports the supramolecular architect of phellopterin and the phenomenon is rarely found in the related structures. Another edge-to-face C21-H21B... interaction link the dimmers through chains as shown in Fig. 4. The face to face... stacking interactions link the planar tricyclic moiety with one another and pack in parallel arrangements. The ring centroids Cg1 and Cg3 look to be trifurcated and the value of show that such type of interactions are weak interactions which show the off-set parallel configurations. The centroid Cg1 and Cg3 are linked to one another through face to face sandwich configuration where as centroid Cg1 is linked to Cg1 and Cg2 through parallel-displaced configurations. Such type of off-set parallel configurations are frequently observed in crystal structures of planar aromatic moieties which support supramolecular structures Conclusions The structure has converged to a good reliability factor i.e. 5.9%. Despite the fact that lot of precession has gone in the development of crystallographic softwares but still the said value a good yield of reliability index. The value of bond angles C2=O2 and C3=C4 in the pyrone rimg of the coumarin moiety are, generally, responsible in the photoactivity of coumarins. In the pyrone ring of the coumarin moiety, O1-C2 and C9-O1 could be due to the involvement of O2 in hydrogen bonding interactions. The C-H...O linear chains packed along bc-plane over different layers of molecule depict the supramolecular structure of phellopterin. The C-H... interactions interlock the phenyloxy side chain with foranocoumarin moiety and the furanocoumarin dimmer are linked to one another through... interactions which depict the supramolecular structure of phellopterin. Acknowledgement The author Bandhan Sharma is thankful to Prof Rajnikant, Department of Physics, University of Jammu, Jammu for providing single crystal diffractometer data of the phellopterin. References 1 Musajo L & Rodighiero G, Herb Hungarica, 19 (1979) Bergendorf O, Photochemistry, 44 (1997) Deckermendjian K, Neurosci Lett, 219 (1996) Kimura Y, J Med Plant Res, 45 (1982) Noguti T & Minoru K, J Pharm Soc, 60 (1940) Gupta B D, Banerjee S K, Handa K L & Atal C K, Ind J of Chem, 16 (1978) Sheldrick G M, SHELXS97, Program for crystal structure determination, University of Gottingen, Federal Republic of Germany, (1997). 8 Farrugia L J, J Appl Cryst, 30 (1997) Nardelli M, J Appl Cryst, 28 (1995) 659.

5 812 INDIAN J PURE & APPL PHYS, VOL 53, DECEMBER Speck A L, PLATON for Windows, University of Ultrecht, The Netherlands (1999). 11 Cox P J, Jaspar M, Kumarasamy Y, Nahar L, Sarker S D & Shoeb M, Acta Cryst, 59 (2003) Rajnikant, Gupta V K, Singh A & Lal M, Mol Materials, 6 (1996) Rajnikant, Dinesh, Shawl A S, Singh T P & Sharma B, J Chem Crystallogr, 35 (2005) Rajnikant, Dinesh, Mousmi, Varghese B & Sharma B, Indian J Phys, 79 (2005) Rajnikant, Dinesh, Kamni and Sharma B, Indian J Pure & Appl Phys, 42 (2004) Berstein J, Etter M C, Leiserowitz L, Burgi H B & Dunitz J D, Weinheim:VCH, 2 (1994) Hunter C A, Singh J & Thompton J M, Mol Biol, 218 (1991) 837.