Research Journal of Recent Sciences ______ ______________________________ ______ ___ __ _ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J. Recent .Sci. International Science Congress Association 67 Synthesis and fluorescent behavior of Pyran and Pyridine - 3, 5 - dicarbonitrile derivatives Shinde Santosh S. and Jachak Madhukar N. Department of Chemistry, K.T.H.M. College, Gangapur Road, Nashik , MS, INDIA Available online at: www.isca.in (Received 30 th September 2011, revised 9 th January 2012 , accepted 27 th January 2012 ) Abstract Novel chalcones were synthesized by Aldol condensation of aromatic aldehydes and the hitherto not described 3 - (2,5 - dimethoxyphenyl) - 3 - oxopropanenitrile in basic medium followed by cyclization with malononitrile to corresponding pyran derivatives. The well characterized p yran derivatives were further transformed into pyridine derivatives by neat heating with ammonium acetate. The fluorescence properties and quantum yield of these synthesized compounds were studied. Keywords: Chalcones, p yrans - 3,5 - dicarbonitriles, pp yridin e - 3,5 - dicarbonitriles, HOMO - LUMO, f luorescence, q uantum yields. Introduction Derivatives of pyridine have application as light emitting diode 1 and in electroluminescence devices 2 . Apart from this, 3 - pyridinedica rbonitriles has been used as dyes for synthetic fabrics 3,4 and in security paper 5,6 . The heterocycles which have high extinction coefficient, large stokes shift and quantum yield near to one are fluorescent brighter and these three parameters largely deter mine color strength and brightness. Heterocycles which fluoresces between 400 to 700nm and have an electron hole gap between 2.7 to 7 eV are suitable for organic light emitting diodes (OLED) 7 . Suitable blue - emitting material with high brightness, low hole gap and high quantum yield still remain to be developed. As a part of our ongoing interest in this area 8,9 , we have reported the synthesis of dipyrazolo [3,4 - b:3,4 - d] pyridines (DPP) 10 and 3 - pyridinecarbonitriles and studied their photophysical properties. Recently, the synthesis and fluorescent behavior of pyrazolo - pyrrolo - pyrimidine (PPP) derivatives 11 has been reported, these literature reports encouraged us to syntheses of novel pyran and pyridine dicarbonitriles and study of their photophysical propert ies. Fig ure - 1 Molecular modeling of pyrans 4(a - g) and pyridine - 3, 5 - dicarbonitriles 5(a - g) Material and Method s Melting points were determined on a Gallenkamp melting point apparatus Mod.MFB595 in open capillary tubes and are uncorrected. 1 H and 13 C NMR Spectra were recorded on Varian XL - 300 spectrometer (300MHz). Infrared spectra were taken on Shimadzu FTIR - 408, instrument in potassium bromide pellets. UV and Fluorescence spectra were recorded on a Shimadzu, UV - 1601 UV - VIS RF - 5301 - PC - Spectrofluorop hotometer respectively; UV and fluorescence scans were recorded between 200 to 600 nm. Mass spectra were recorded on a Shimadzu GC - MS QP 2010A mass spectrometer with an ionization potential of (70eV). Solutions were concentrated in a rotary evaporator un der reduced pressure. All reactions were monitored by thin layer chromatography, carried out on 0.2 mm silica gel 60 F 254 (Merck) plates using UV light (250 and 400 nm) and fluorescence light (400 and 600 nm) for detection. Common reagents grade chemicals are either commercially available and were used further purification or prepared by standard literature procedures. The GAMESS software (MOPAC - 2009, PM6) is used for HOMO - LUMO, by semi empirical methods General Procedure for the synthesis of Chalcone 3a - g: A mixture of compound 1 (0.001 mole) and aromatic aldehydes 2(a - g) (0.001mole) in ethanol (10 ml) containing 2 - 3 drops of piperidine was heated for 4 - 5 h (TLC toluene: acetone, 9:1), then reaction mixture was cooled at room temperature. The solid obtai ned was isolated by filtration, dried and recrystallized from ethanol to afford as pale yellow prisms in 70 - 80% yields. Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J.Recent.Sci International Science Congress Association 68 (3 E ) – 4 - ( 4 - Chlorophenyl) - 3 - [(2, 5 - dimethoxyphenyl) carbonyl] but - 3 - enenitrile (3a) : Yield: 0.245g (75%), mp. 106 - 108 C. ir (potassium bromide): 2940, 2210, 1676, 1610, cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.32 (s, 3H, OCH 3 ), 3.73 (s, 3H, OCH 3 ), 6.85( s, 1H, CH) 6.95 (dd, 1H, J = 2.3 & 8.2 Hz, Ar - H), 7.12 (d, 1H, J = 8.2 Hz, Ar - H), 7.13 (d, 1H, J = 2.3 Hz, Ar - H), 7.16 (d, 2H, J = 8.5Hz, Ar - H), 7.72 (d, 2H, J = 8.5 Hz, Ar - H) ppm; MS(70 eV): m/z 327 (M + ). Anal.Calcd for C 18 H 14 ClNO 3 (327.76): C, 66.05; H, 4.28; N, 4.28 Found C, 66.02; H, 4.31, N, 4.30. (3 E ) – 4 - ( 4 - Bromophenyl) – 3 - [(2 , 5 dimethoxyphen yl) carbonyl]but - 3 - e nenitrile(3b) : Yield: 0.267g (72%), mp.130 - 132C. ir (potassium bromide): 3010, 2211, 1722,1605, cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.35 (s, 3H, OCH 3 ), 3.76 (s, 3H, OCH 3 ), 6.80 ( s, 1H, CH) 6.94 (dd, 1H, J = 2.5 & 8.1 Hz, Ar - H), 7.14 (d, 1H, J = 8.1 Hz, Ar - H), 7.16 (d, 1H, J = 2.5 Hz, Ar - H), 7.18 (d, 2H, J = 8.8 Hz, Ar - H), 7.78 (d, 2H , J = 8.8 Hz, Ar - H) ppm; MS(70eV): m/z 372 (M + ). Anal.Calcd for C 18 H 14 O 3 NBr (372.21): C, 58.06; H, 3.76; N, 3.76. Found C, 58.08; H, 3.77; N, 3.77. (3 E ) – 3 - [(2 ,5 – D ime thoxyphenyl) carbonyl] – 4 - (4 - fluoro phenyl) but - 3 - enenitrile(3c) : Yield:0.233g(75%),m.p.124 - 126C. ir (potassium bromide):3002, 2227,1715,1608 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.36 (s, 3H, OCH 3 ), 3.75 (s, 3H, OCH 3 ), 6.75 ( s,1H,CH ) 6.96 (dd, 1H, J = 2.1& 8.4 Hz, Ar - H), 7.16 (d, 1H, J = 8.4 Hz, Ar - H), 7.18 ( d, 1H , J = 2.1 Hz, Ar - H), 7.15 (d, 2H, J = 8.5 Hz, Ar - H) 7.79 (d, 2H, J = 8.5 Hz, Ar - H) ppm; MS(70 eV): m/z 311(M + ). Anal.Calcd for C 18 H 14 O 3 NF (311.31): C, 69.45; H, 4.50; N, 4.50. Found C, 69.4 1; H, 4.52; N, 4.51. (3 E ) - 3 - [(2,5 - Dimethoxyphenyl) carbonyl] - 4 - (3 - ethoxyph enyl)but - 3 - enenitrile(3d) : Yield: 0.239g (74%), mp.103 - 105C. ir (potassium bromide): 3040,2226,1730,1615cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.37 (s, 3H, OCH 3 ), 3.78 (s, 3H, OCH 3 ), 3.97 (s, 3H, OCH 3 ), 6.82 ( s, 1H, CH ), 6.96 (dd, 1H, J = 2.7 & 8.1 Hz, Ar - H), 7.11 (d, 2H, J = 8.1 Hz, Ar - H), 7.16 (d, 1H, J = 2.7 Hz, Ar - H), 6.69 ( d, 1H, J = 8.8 Hz, Ar - H), 6.77 (s, 1H, Ar - H), 7.21 (dd, 1H, J = 8.6 & 8.8 Hz, Ar - H), 7.28 (d, 1H, J = 8.6 Hz, Ar - H) ppm; MS(70eV): m/z 323 (M + ). Anal.Calcd for C 19 H 17 O 4 N (323.31): C, 70.80; H, 5.27; N,4.34. Found C, 70.81; H, 5.26; N, 4.36. (3 E ) - 4 - (3,4 - Dimethoxyphenyl) - 3 - [(2,5 dimethoxyphenyl) carbonyl] but - 3 - enenitrile(3e) : Yield: 0.253g (78%), mp. 99 - 101C. ir (potassium bromide): 2980, 2216, 1605,1710cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.32 (s, 3H, OCH 3 ), 3.73(s, 3H, OCH 3 ), 3.78 (s, 3H, OCH 3 ), 3.86 (s, 3H, OCH 3 ), 6.82 ( s,1H, CH ) 6.95 (dd, 1H, J = 2.3 & 8.1Hz, Ar - H), 7.12 (d, 1H, J = 8.1 Hz, Ar - H), 7.13 (d, 1H, J = 2.3 Hz, Ar - H), 7.16 (d, 1H, J = 8.5 Hz, Ar - H), 7.72 (d, 1H, J = 2.5 Hz, Ar - H), 7.49 (dd, 1H, J = 8.5 & 2.5 Hz, Ar - H) ppm; MS(70eV): m/z 353 (M + ). Anal.Calcd for C 20 H 19 O 5 N (353.37): C,67.98; H, 5.38; N,3.96. Found C,67.96 ; H, 5.36; N,3.95. (3 E ) – 3 - [ (2,5 - Dimethoxyphenyl) carbonyl] - 4 - (4 - nitro phenyl) but - 3 - enenitrile(3f) : Yield:0.260g(77%),mp.107 - 109C.ir(potassiumbromide):2990,2250,1730,1612,1535,136 0 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.39 (s, 3H, OCH 3 ), 3.69 (s, 3H, OCH 3 ), 6.76 (s, 1H, CH), 6.98 (dd, 1H, J = 2.3 & 8.5 Hz, Ar - H), 7.22 (d, 1H, J = 8.5 Hz, Ar - H), 7.53 (d, 1 H, J = 2.3 Hz, Ar - H), 7.76 (d, 2H, J = 8.8 Hz, Ar - H), 7.82 (d, 2H, J = 8.8 Hz, Ar - H) ppm; MS (70eV): m/z 338 (M + ). Anal.Calcd for C 18 H 14 O 5 N 2 (338.31): C, 63.90; H, 4.14; N, 8.28. Found C, 63.87; H, 4.16; N, 8.30. (3 E ) - 3 - [(2,5 - Dimethoxyphenyl)carbonyl] - 4 - phenylbut - 3 - enenitrile(3g) : Yield: 0.233g (80%), mp.102 - 105C. ir (potassium bromide): 2996,2250,1730,1614 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.75 (s, 3H, OCH 3 ), 3.74 (s, 3H, OCH 3 ), 6.78 (s, 1H, CH), 6.85 (d, 1H, J = 2.1 Hz, Ar - H), 7.05 (dd, 1H, J = 2.1 & 8.4 Hz, Ar - H), 7.34 (m, 3H, Ar - H), 7.36 (d, H, J = 8.4 Hz, Ar - H), 7.51 (m, 2H, Ar - H) ppm; MS (70eV): m/z 292 (M + ). Anal. Calcd for C 18 H 14 O 3 N (292.31): C, 73.72; H, 4.77; N, 4.77. Found C, 73.71; H, 4.75; N, 4.76. General Procedure for the synthesis of Pyran 4a - g : A mixture of chalcone 3 (0.001 mole) and malononitrile (0.001mole) in ethanol (10 mL) containing catalytic amount of ethanolic potassium hydroxide (50mg of KOH was dissolved in 2 mL ethanol) was stirred at room temperature for 5 - 6 h (TLC, toluene:acetone, 9:1). The solid obtained was collected by filtration, dried and recrystallized from ethanol to furnish 4 as a colorless solid in 80 - 85%. 2,2' - [2 - Amino - 4 - (4 - chlorophenyl) - 6 - (2, 5 dimethoxyphenyl - 4 H - pyran – 3 ,5 diyl] diacetonitrile (4a) : Yield: 0.314g (80%), mp. 93 - 95 C. ir (potassium bromide): 3312, 3280, 2240, 1640, 1560 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.70 (s, 3H, OCH 3 ), 3.75 (s, 3H, OCH 3 ), 4.75 (s, 1H, CH), 7.13 (d, 1H, J = 2.5 Hz, Ar - H), 7.21 (dd, 1H, J = 2.5 & 8.5 Hz, Ar - H), 7.29 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.5 Hz, Ar - H), 7.51 (d, 2H, J = 8.2 Hz, Ar - H), 7.65 (d, 2H , J = 8.2 Hz, Ar - H) ppm; MS (70 eV): m/z 393 (M + ). Anal.Calcd for C 21 H 16 ClN 3 O 3 (393.82): C, 64.12; H, 4.07; N, 10.68. Found C, 64.10; H, 4.06; N, 10.66. 2,2' - [2 - Amino - 4 - (4 - bromophenyl) - 6 - (2,5 dimethoxyphe n - yl) - 4 H - pyran - 3,5diyl] - diacetonitrile (4b): Yield: 0.359g (82%), mp.115 - 117 C. ir (potassium bromide): 3302, 3285, 2240, 1630, 1590 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.75 (s, 3H, OCH 3 ), 3.81 (s, 3H, OCH 3 ), 4.75 (s, 1H, CH), 7.33(d, 1H, J = 2.7 Hz, Ar - H), 7.22 (dd, 1H, J = 2.7 & 8.4 Hz, Ar - H), 7.27(bs, 2H, NH 2 ), 7.35 (d, 1H, J = 8.4 Hz, Ar - H), 7.55(d, 2H, J = 8.3 Hz, Ar - H), 7.75(d, 2H, J = 8.3 Hz, Ar - H) ppm; MS (70eV): m/z 438 (M + ). Anal.Calcd for C 21 H 16 BrN 3 O 3 (438.27): C, 57.53; H, 3.65; N, 9.58. Found C, 57.54; H, 3.67; N, 9.57. Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J.Recent.Sci International Science Congress Association 69 2,2' - [2 - Ami no - 6 - (2,5 - dimethoxyphenyl) - 4 - (4 fluo rophenyl - 4 H - pyran - 3,5diyl] - diacetonitrile(4c) : Yield: 0.316g (84%), mp.125 - 127 C. ir (potassium bromide): 3286, 3240, 2235, 1605, 1560 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.72 (s, 3H, OCH 3 ), 3.80 (s, 3H,OCH 3 ), 4.88 (s, 1H, CH), 7.10 (d,1H, J = 2.5 Hz, Ar - H), 7.12 (dd, 1H, J = 2.5 & 8.5 Hz, Ar - H), 7.29 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.5 Hz, Ar - H), 7.54 (d, 2H, J = 8.2 Hz, Ar - H), 7.65 (d, 2H, J = 8.2 Hz, Ar - H) ppm; MS (70eV): m/z 377 (M + ). Anal.Calcd for C 21 H 16 FN 3 O 3 (377.37): C, 67.02; H, 4.25 ; N, 11.17. Found C, 67.01; H, 4.24; N, 11.18. 2,2' - [2 - Amino - 6 - (2,5 - dimethoxyphenyl) - 4 - (3 - methoxy - phenyl) - 4 H - pyran - 3,5 - diyl] - diacetonitrile(4d) : Yield: 0 .315g (81%), m.p. 111 - 114 C. ir (potassium bromide): 3286, 3190, 2245, 1620 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.70 (s, 3H, OCH 3 ), 3.79 (s, 3H, OCH 3 ), 3.94 (s, 3H, OCH 3 ), 5.02 (s, 1H, CH), 6.82 (s, 1H, Ar - H), 6.94 (d, 1H, J = 8.2 Hz, Ar - H), 7.05 (dd, 1H, J = 8.2 & 8.4 Hz, Ar - H), 7.09 (d, 1H, J = 8.4 Hz, Ar - H), 7.12 (d, 1H, J = 2.5 Hz, Ar - H), 7.19 (dd, 1H, J = 2.5 & 8.8 Hz, Ar - H), 7.25 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.8 Hz, Ar - H) ppm; MS (70eV):m/z 389 (M + ). Anal.Calcd forC 22 H 19 N 3 O 4 (389.40): C, 67.86; H, 4.88; N, 10.79. Found C, 67.85; H, 4.87; N, 10.76. 2,2' - [2 - Amino - 6 - (2,5 - dimethoxyphenyl) - 4 (3,4dimetho xy phenyl) - 4 H - pyran - 3,5 - diyl] - diacetonitrile (4e) : Yield: 0.343g (82%), m.p. 103 - 105 C. ir (potassium bromide): 3260, 3180, 2245, 1600 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.41 (s, 3H, OCH 3 ), 3.52 (s, 3H, OCH 3 ), 3.58 (s, 3H, OCH 3 ), 3.82 (s, 3H, OCH 3 ), 4.68 (s, 1H, CH), 6.84 (dd, 1H, J = 2.3 & 8.4 Hz, Ar - H), 7.12 (d, 1H, J = 8.4 Hz, Ar - H), 7.13 (d, 1H, J = 2.3 Hz, Ar - H), 7.20 (d, 1H, J = 2.5 Hz, Ar - H), 7.21 (bs, 2H, NH 2 ), 7.27 (dd, 1H, J = 2.5& 8.7 Hz, Ar - H), 7.32 (d, 1H, J = 8.7 Hz, Ar - H) ppm; 13 C nmr (75MHz, CDCl 3 ) δ : 55.45, 55.67, 56.06, 56.30, 93.87, 111.15, 111.92, 113.14, 115.16, 116.15, 117.23, 119.43, 119.21, 120.11, 129.12, 134.32, 136.78, 148.39, 148.84, 150.25, 152.21, 155.09, 158.56. ppm; MS (70 eV): m/z 419 (M + ). Anal.Calcd for C 23 H 21 N 3 O 5 (419.43): C, 65.87; H, 5.01; N, 10.02. Found C, 65.86; H, 5.03; N, 10.01. 2,2' - [2 - Amino - 6 - (2,5 - dimethoxyphenyl) - 4 - (4 - nitrophen z - yl) - 4 H - pyran - 3,5 - diyl] - diacetonitrile(4f) : Yield: 0.342g (85%), mp. 130 - 132C. ir (potassium bromide): 3255, 3150, 2240, 1605, 1540, 1315 cm - 1 . 1 H nmr ( DMSO - d 6 )  =: 3.75 (s, 3H, OCH 3 ), 3.81 (s, 3H, OCH 3 ), 4.75 (s, 1H, CH), 7.13 (d, 1H, J = 2.7 Hz, Ar - H), 7.12 (dd, 1H, J = 2.7 & 8.7 Hz, Ar - H), 7.27 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.7 Hz, Ar - H), 7.51 (d, 2H, J = 8.2 Hz, Ar - H), 7.68 (d, 2H, J = 8.2 Hz, Ar - H) ppm; MS (70eV): m/z 404 (M + ). Anal.Calcd for C 21 H 16 N 4 O 5 (404.38): C, 62.53 H, 3.97; N, 13.89. Found C, 62.52 H, 3.95; N, 13.85. 2,2' - [2 - Amino - 6 - (2,5 - dimethoxyphenyl) - 4 - phenyl - 4 H - pyran - 3,5 - diyl]diacetonitri le (4g) : Yield: 0.290g (81%), mp. 112 - 115C. ir (potassium bromide): 3285, 3180, 2235, 1615 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.70 (s, 3H, OCH 3 ), 3.74 (s, 3H, OCH 3 ), 4.64 (s, 1H, CH), 6.85 (d, 1H, J = 2.3 Hz, Ar - H), 7.05 (dd, 1H, J = 2.3 & 8.3 Hz, Ar - H), 7.24 (bs, 2H, NH 2 ), 7.38 - 7.52 (m, 5H, Ar - H), 7.36 (d, 2H , J = 8.3 Hz, Ar - H) ppm; 13 CNMR ( DMSO - d 6 ) δ : 55.79, 56.31, 93.24, 113.44, 115.54, 116.52, 117.82, 118.98, 120.17, 127.68, 127.78, 128.86, 142.25, 150.98, 152.77, 156.08, 158.53. ppm; MS (70 eV): m/z 359 ( M + ). Anal.Calcd for C 21 H 17 N 3 O 3 (359.38): C,70.19; H, 4.73; N, 11.69. Found C, 70.17; H, 4.71; N, 11.68. General Procedure for synthesis of pyridine 3, 5 - dicarbonotrile 5a - g : A mixture of pyran 4 (0.001 mole) and ammonium acetate (0.01 mole) was heated at 110 - 120C for 5 - 6 h. After completion of reaction (TLC) cold water (30 mL) was added to the viscous reaction mixture and stirred for further 30 - min to remove excess of ammonium acetate. Then it was extracted with ethyl acetate, organic layer was dried ove r anhyd. Sodium sulphate and evaporated to furnish yellow solid. It was recrystallized from ethanol to furnish compound 5 in 80 - 85% yields. 2 - Amino - 4 - (4 - chlorophenyl) - 1,4 - dihydro - 6 - (2,5 - dimetho xyphenyl)pyridine - 3,5 - dicabonitrile(5a) : Yield: 0.313g (80%), m.p. 117 - 116C. ir (potassium bromide): 3440 , 3312, 3275, 2245, 1640,1570 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.71 (s, 3H, OCH 3 ), 3.73 (s, 3H, OCH 3 ), 4.66 (s, 1H, CH), 6.88 (d, 1H, J = 2.3 Hz, Ar - H), 7.10 (dd, 1H, J = 2.3 & 8.5 Hz, Ar - H), 7.29 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.5 Hz, Ar - H), 7.49 (d, 2H, J = 8.9 Hz, Ar - H), 7.64 (d, 2H, J = 8.9 Hz, Ar - H), 9.86 (bs, 1H, NH) ppm; MS(70eV): m/z 392 (M + ). Anal.Calcd. for C 21 H 17 ClN 4 O 2 (392.84): C, 64.28; H, 4.33; N, 14.28. Found C, 64.27; H,4.32; N, 14.26. 2 - Amino - 4 - (4 - bromophenyl) - 1,4 - dihydro - 6 - (2,5 - dimetho - xyphenyl)pyridine - 3,5 - dicabonitrile (5b) : Yield: 0.358g (82%), m.p. 154 - 155C. ir (potassium bromide): 3392 , 3304, 3225, 2235, 1640, 1575 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.72 (s, 3H, OCH 3 ), 3.74 (s, 3H, OCH 3 ), 4.64 (s, 1H, CH), 6.85 (d, 1H, J = 2.2 Hz, Ar - H), 7.05 (dd, 1H, J = 2.2 & 8.4 Hz, Ar - H), 7.27 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.4 Hz, Ar - H), 7.44 (d, 2H, J = 8.7 Hz, Ar - H), 7.59 (d, 2H, J = 8.7 Hz, Ar - H), 9.88 (s, 1H, NH) ppm; MS(70eV): m/z 437 (M + ). + ). Anal.Calcd for C 21 H 17 BrN 4 O 2 (437.29): C, 57.66; H, 3.89; N, 12.81. Found C, 57.65; H, 3.87; N, 12.80. 2 - Amino - 4 - (4 - fluorophenyl) - 1,4 - dihydro - 6 - (2,5 - dime - thoxyphenyl)pyridine - 3,5 - dicabonitrile (5c) : Yield: 0.319g (85%),m.p.142 - 143C. ir (potassium bro mide): 3384, 3325, 3265, 2250, 1610, 1550, 1325 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.77 (s, 3H, OCH 3 ), 3.71 (s, 3H, OCH 3 ), 4.62 (s, 1H, CH), 6.82 (d, 1H, J = 2.3 Hz, Ar - H), 7.15 (dd, 1H, J = 2.3 & 8.2 Hz, Ar - H), 7.30 (bs, 2H, NH 2 ), 7.32 (d, 1H, J = 8.2 Hz, Ar - Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J.Recent.Sci International Science Congress Association 70 H ), 7.39 (d, 2H, J = 8.8 Hz, Ar - H), 7.72 (d, 2H, J = 8.8 Hz, Ar - H), 9.85 (s, 1H, NH) ppm; MS (70eV): m/z 376 (M + ). Anal. Calcd. for C 21 H 17 FN 4 O 2 (376.38): C, 67.02; H, 4.52; N, 14.89. Found C, 67.01; H, 4.53; N, 14.86. 2 - Amino - 1,4 - dihydro - 6 - (2,5 - dimethoxyphenyl) - 4(3metho - xyphenyl)pyridine - 3,5 - dicabonitrile(5d) : Yield: 0.322g (83%). m.p.123 - 124C. ir (potassium bromide): 3410, 3310, 3265, 2242, 1635, 1560 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.77 (s, 3H, OCH 3 ), 3.81 (s, 3H, OCH 3 ), 3.91 (s, 3H, OCH 3 ), 4.75 (s, 1H, CH), 6.82 (d, 1H, J = 8.2 Hz, Ar - H), 6.90 (s, 1H, Ar - H), 6.94 (dd, 1H, J = 8.2 & 8.4 Hz, Ar - H), 7.12 (d, 1H, J = 8.4 Hz, Ar - H), 7.13 (d, 1H, J = 2.5 Hz, Ar - H), 7.12 (dd, 1H, J = 2.5 & 8.5 Hz, Ar - H), 7.25 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.5 Hz, Ar - H), 9.92 (s, 1H, NH) ppm; MS(70eV): m/z 388 (M + ). Anal.Calcd for C 22 H 20 N 4 O 3 (388.42): C, 68.04; H, 5.15; N, 14.43. Found C, 68.03; H, 5.12; N, 14.42. 2 - Amino - 1,4 - dihydro - 6 - (2,5 - dimethoxyphenyl) - 4 - (3,4 - dime - thoxyphenyl) - pyri dine - 3,5 - dicabonitrile(5e) : Yield: 0.334g (80%), m.p.128 - 129 C. ir (potassium bromide): 3408, 3322, 3255, 2245, 1635,1595 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.41 (s, 3H, OCH 3 ), 3.52 (s, 3H, OCH 3 ), 3.58 (s, 3H, OCH 3 ), 3.82 (s, 3H, OCH 3 ), 4.68 (s, 1H, CH), 6.84 ( dd, 1H, J = 2.5 & 8.4 Hz, Ar - H), 7.12 (d, 1H, J = 8.4 Hz, Ar - H), 7.13 (dd, 1H, J = 2.4 & 8.2 Hz, Ar - H), 7.20 (d, 1H, J = 2.5 Hz, Ar - H), 7.27 (d, 1H, J = 8.2 Hz, Ar - H), 7.29 (bs, 2H, NH 2 ), 7.32 (d, 1H, J = 2.4 Hz, Ar - H), 9.90 (s, 1H, NH) ppm; 13 C nmr ( DMSO - d 6 ) δ : 55.01, 45.05, 55.08, 67.14, 56.06, 56.30, 93.09, 111.15, 111.92, 113.01, 115.08, 116.05, 117.12, 119.09, 119.22, 120.23, 134.31, 148.39, 148.84, 150.06, 152.08, 155.33, 158.21 ppm; MS(70eV):m/z 418 (M + ). Anal.Calcd for C 23 H 22 N 4 O 4 (418.45): C, 6 6.02; H,5.26; N, 13.39. Found C, 66.01; H,5.24; N, 13.34. 2 - Amino - 1,4 - dihydro - 6 - (2,5 - dimethoxyphenyl) - 4 - (4 - nitrophenyl)pyridine - 3,5 - dicabonitrile (5f) : Yield: 0.338g (84%). m.p158 - 159C. ir (potassium bromide): 3398, 3305, 3275, 2250, 1640, 1520, 1350 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.69 (s, 3H, OCH 3 ), 3.74 (s, 3H, OCH 3 ), 4.61 (s, 1H, CH), 6.85 (d, 1H, J = 2.5 Hz, Ar - H), 7.15 (dd, 1H, J = 2.5 & 8.6 Hz, Ar - H), 7.27 (bs, 2H, NH 2 ), 7.38 (d, 1H, J = 8.6 Hz, Ar - H), 7.47 (d, 2H, J = 8.9 Hz, Ar - H), 7.89(d, 2H, J = 8.9 Hz, Ar - H), 9.86 (s, 1H, NH) ppm; MS(70eV): m/z 403 (M + ). Anal.Calcd for C 21 H 17 N 5 O 4 (403.39): C, 62.37; H,4.49; N,17.32. Found C, 62.61; H,4.52; N,17.21. 2 - Amino - 1,4 - dihydro - 6 - (2,5 - dimethoxyphenyl) - 4 - phenylpyridine - 3,5 - dicabonitrile(5g) : Yield: 0.289g (81%), mp. 138 - 139C. ir (potassium bromide): 3398, 3310, 3250, 2245, 1635 cm - 1 . 1 H nmr ( DMSO - d 6 ):  = 3.71 (s, 3H, OCH 3 ), 3.73 (s, 3H, O CH 3 ), 4.60 (s, 1H, CH), 6.81 (d, 1H, J = 2.4 Hz, Ar - H), 7.15 (dd, 1H, J = 2.4 & 8.7 Hz, Ar - H), 7.24 (m, 3H, Ar - H), 7.29 (bs, 2H, NH 2 ), 7.36 (d, 1H, J = 8.7 Hz, Ar - H), 7.51 (m, 2H, Ar - H), 9.84 (s, 1H, NH) ppm; MS (70eV): m/z 358 (M + ). Anal.Calcd for C 21 H 18 N 4 O 2 (358.39): C, 70.39;H, 5.02; N, 15.64. Found C, 70.37; H, 5.03; N, 15.62. Results and Discussion The required chalcones for the synthesis of title compounds were prepared by aldol condensation of 3 - (2,5 - dimethoxyphenyl) - 3 - oxopropanenitrile and aromatic aldehydes. Thus, equimolar solution of 3 - (2,5 - dimethoxyphenyl) - 3 - oxopropaneni trile 1 and aromatic aldehydes 2 in ethanol, heating in basic medium furnished chalcones 3 in 70 - 80 % yield ( s cheme 1). Compounds 3 were characterized by spectral and analytical methods. The chalcones 3 , were further utilized for Michael addition with malo nonitrile in presence of catalytic amount of KOH in ethanol to yield pyran derivatives 4 in 80 - 85 % yield. Previously we have noted the formation of pyridine derivative by condensation of chalcone, different than reported here, with malononitrile under sim ilar reaction condition, Compounds 4 were transformed in to pyridine derivative 5 by heating with ammonium acetate at 110 - 120 C ( s cheme 1). This reaction did not require any solvent and aqueous work up of the reaction allowed for the isolation of 100 % of the product 5 .and were characterized by IR, mass, 1 H and 13 C NMR data. Further semiempircal study and photophysical properties of compounds 4 and 5 were under taken. Scheme - 1 Scheme - 1 Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J.Recent.Sci International Science Congress Association 71 Table - 1 The molecular electronic properties (HOMO - LUMO energy and GAP value) of pyrans 4(a - g) and pyridine - 3,5 - dicarbonotriles 5(a - g) Comp. R 1 R 2 HOMO eV LUMO eV GAP eV 4a H Cl - 8.898 - 1.086 7.812 4b H Br - 8.894 - 1.088 7.806 4c H F - 8.887 - 1.071 7.816 4d OMe H - 8.775 - 0.951 7.824 4e OMe OMe - 8.257 - 0.932 7.325 4f H NO 2 - 9.224 - 1.319 7.905 4g H H - 8.819 - 0.979 7.840 5a H Cl - 8.910 - 1.042 7.868 5b H Br - 8.920 - 1.054 7.866 5c H F - 8.890 - 1.024 7.866 5d OMe H - 8.660 - 0.914 7.746 5e OMe OMe - 8.150 - 0.897 7.253 5f H NO 2 - 9.170 - 1.288 7.882 5g H H - 8.805 - 0.938 7.867 Table - 2 The photophysical data for electronic absorption (UV  Max . ), fluorescence (Em  Max . ) and quantum yield (  F ) of pyran 4(a - g) and pyridine - 3,5 - dicarbonotrile 5(a - g) for 0.1M Conc. in CHCl 3 at 25C. Comp. R 1 R 2  Abs. (CHCl 3 ) N m  Emi. (CHCl 3 ) nm  F 4a H Cl 358 nm 445 0.171 4b H Br 359 nm 448 0.173 4c H F 353 nm 451 0.174 4d OMe H 357 nm 464 0.186 4e OMe OMe 367 nm 475 0.197 4f H NO 2 344 nm 423 0.151 4g H H 358 nm 456 0.181 5a H Cl 406 nm 455 0.177 5b H Br 376 nm 453 0.175 5c H F 358 nm 457 0.178 5d OMe H 381 nm 469 0.189 5e OMe OMe 413 nm 479 0.208 5f H NO 2 347 nm 430 0.156 5g H H 355 nm 461 0.184 Semi - empirical study : The gain interest into the atomic contribution on the frontier orbital, we analyzed the three - dimensional HOMO and LUMO coefficient contribution by software MOPAC - 2009 (Version 8.331) and are given in t able 1. From this table we observed that pyran derivative 4e and pyridine - 3, 5 - dicarbonitriles 5e showed low gap values (eV= 7.325 and 7.253), while compounds 4f and 5f showed high gap values (eV= 7.905 and 7.882). The observed low gap value for 4e and 5e may be due to strong electron donating group such as - OCH 3 and high gap value for 4f and 5f due to – NO 2 group which is electron acceptor present on ring C ( f ig ure - 1) The 3D picture (molecular modeling)of representative pyran and pyridine dicarbonitriles . Photophysical properties : F luorescence quantum yields of compound 4 and 5 were determined by standard literature procedure using quinine sulphate as reference standard and are listed in t able 2. From this table we observed that compound 4e and 5e showed m aximum absorption, emission and high quantum yields (  F = 0.197 & 0.208 respectively). This may be due to electron donating group ( - OCH 3 ) present on benzene ring at C 4 - position in ring C of pyran 4e and pyridine 5 e (fig ure - 1). The electron accepting group such as - NO 2 on benzene ring at C 4 - position in 4f and 5f showed absorption, emission to shorter wavelength also low quantum yields (  F = 0.151 and 0.156 respectively). The graphical representation of absorption and emission spectra of compound 4e and 5e a re shown in fig ure 2. f igure - 2. Comparative absorption (UV  Max) and emission (Em  Max) spectra of compounds (4e) and (5e) respectively. Conclusion In summary we have developed an efficient and simple method for synthesis of pyran derivatives 4 in excellent yields, the transformation of 4 in to pyridine derivative 5 was achieved using ammonium acetate as ecofriendly reagent. This method has several advantages in terms of yields, mild reaction condition and lack of side product. The photophysical studies of compound 4 an 5 revealed that the donor substituents – OCH 3 on benzene ring at C 4 - position (C - ring, figure - 1) of 4e and 5e showed red shift (Bathochromic shift), while acceptor group – NO 2 leads to absorption and emission to shorter wavelength i. e. blue shift (hypsochromic shift). From these studies we can conclude that the Research Journal of Recent Sciences ______ _ _ _______________________________ ______________ _ ______ ISSN 2277 - 2502 Vol. 1( ISC - 2011 ), 67 - 72 (201 2 ) Res.J.Recent.Sci International Science Congress Association 72 fluorescent properties of compounds 4 and 5 depend upon the nature of substituents present on benzene ring at (C - ring, f ig ure - 1) C 4 - position of pyran and pyridine nucleus. Thes e compounds may be useful as organic light emitting diodes (OLED) and are addition in the library of new heterocyclic compounds. Acknowledgements The authors thank UGC and DST New Delhi, for the financial support and Prof . D. 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