Phthalocynines and perylenes constitute an important group of industrial dyes with broad ranging activities. The research work reported in the thesis comprises three parts. First part comprised of the synthesis of various substituted phthalocyanines and in the second part perylene based dyes were synthesized. In part three, the potential of the selected synthesized compounds for applications in organic electronics was demonstrated. In order to synthesize phthalocynine dyes various precursors including 4- [(6-hydroxyhexylamino)methyl]phthalonitrile,(130) 4-[(9,10-dioxo-9,10- dihydroanthracen-2-ylamino)methyl]phthalonitrile,(131) 4-({1-[(4- nitrophenyl)diazenyl]naphthalen-2-yloxy}methyl)phthalonitrile,(132) 4-({4-[(4- nitrophenyl)diazenyl]naphthalen-1-yloxy}methyl)phth alonitrile (133) 4-(pyrrolidin- 1-yl)phthalonitrile, (126) 4-(piperidin-1-yl)phthalonitrile (127) and 4-(azepan-1- yl)phthalonitrile (128) were prepared. These precursors were then cyclotetramerized by refluxing in the presence of metal chlorides (where required) in nitrobenzene to obtain substituted metallated and non metallated phthalocyanines (152-169, 189-196) (Scheme-I). iR CN R PhNO 2 , MCl 2 6 Hrs reflux CN R N N N M N N N N O H N R R R = HO-(CH 2 ) 6 - NHCH 2 −, N− N CH 2 − M = 2H, Cu, Ni, Zn, Co, Pb. N− O N− Scheme I 2(3),9(10),16(17),23(24)-Tetra(chlorosulfonyl)phthalocyanines (170) were prepared from the chlorosulfonylation of unsubstituted phthalocyanines. The tetra(chlorosulfonyl)phthalocyanines (170) were then hydrolyzed to obtain 2(3),9(10),16(17),23(24)-tetrasulfophthalocyanines (146-151). 2(3),9(10),16(17),23(24)-Tetra(octylaminosulfonyl)-, (171-182) 2(3),9(10),16(17),23(24)-tetra(6-hydroxyhexylaminosulfonyl)- (183-188) and 2(3),9(10),16(17),23(24)-tetra(p-sulfophenylaminosulfonyl)phthalocyanines (171- 176) (metallated and metal tetrachlorosulfonylphthalocyanines free) were prepared by reacting the with aminooctane, 6-aminohexanol and 4- amniobenzenesulfonic acid respectively (Scheme-II). iiSO 2 Cl ClO 2 S N N N M N N ClSO 3 H N N N Reflux, 10 hrs N N N M N N N N N SO 2 Cl ClO 2 S r.t RH NH SO 2 R NH(CH 2 ) 5 -CH 3 , NH(CH 2 ) 7 -CH 3 , OH R = RO 2 S SO 3 H N M = 2H, Cu, Ni, Zn, Co, Pb. N N M N N N N N SO 2 R RO 2 S Scheme II In the second phase few alkylated perylene diimides were synthesized from perylene-3,4,9,10-tetracarboxylic acid dianhydride (Scheme-III) to study their applications in organic electronics. aggregational behavior of non- alkylated and alkylated perylene dyes. iiiO O O O O O NH 2 -(CH 2 )n-CH 3 O O n(H 2 C) N O H 3 C O O n = 3, 7. NH 2 -(CH 2 ) 6 -OH NH 2 -(CH 2 ) 6 -R O O (H 2 C) 6 N N (CH 2 ) 6 HO O O (H 2 C) 3 OH H 3 C O O N N (CH 2 ) 6 O O R R = OH, NH 2 . (Scheme III) All precursors (Phthalonitriles) were characterized by IR, NMR, Mass and elemental analysis while structure final products were established by UV/Vis, IR, Mass and elemental analysis. In phase three of this research, investigation of the selected synthesized organic semiconducting materials for potential applications in organic electronics was undertaken. In this thesis, fabrication and characterization of Au/K 4 NiPTS/Ag, Au/K 4 NiPTS/Au and N-BuPMIMA/p-Si surface type Schottky barrier diode, surface type capacitive humidity sensor and heterojunction, respectively, is reported. Current-voltage (I-V) characteristics of the Au/K 4 NiPTS/Ag Schottky diode are studied. The device has shown rectification behavior. Interpretation of the charge transportation in K 4 NiPTS is provided. From the I-V curves the diode parameters are extracted. This has successfully demonstrated the potential of the synthesized organic semiconductor reported in this thesis for a wide range of Schottky diode based electronic and photonic devices of current industrial importance. Effect of relative humidity on the capacitance of the surface-type Au/K 4 NiPTS/Au sensor is investigated. It is observed that the capacitance of the ivsensor increases with the rise in humidity level. Humidity dependent capacitance properties of this sensor make it attractive for use in humidity sensors.Current- voltage (I-V) characteristics of the N-BuPMIMA/p-Si heterojunction are studied. The device has shown rectification behavior. Interpretation of the charge transport through N-BuPMIMA is provided. Further work on the fabrication of a number of organic electronic devices including Schottky diodes, heterojunctions, sensors and organic field effect transistors using the synthesized organic semiconducting materials reported in this thesis, is in progress.