Abstract:
The present invention relates to pyrrole derivatives, particularly 2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole derivatives, which has metallic luster, good stability in air, and a high solubility in an organic solvent, and which is suitable for a film-forming material.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to metallically-lustered pyrrole derivatives, particularly 2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole derivatives, which can be used for a coating material, organic metal plating material, organic semiconductor material or the like. 
     2. Description of Related Art 
     It has been known that a high-molecular weight compound having a conjugated π-electron system in the molecule thereof has a metallic luster. Because the metallic luster in such a compound is based on free electrons in the π-electron system, the compound is expected to have semiconductor-like properties. Poly(acetylene), poly(sulfur nitride) and the like are examples of such a compound. 
     SUMMARY OF THE INVENTION 
     Since they are unstable in doped and even undoped states, organic compounds having metallic luster which are stable even in air are demanded. 
     Further, since the high-molecular weight compound having a π-electron conjugated system generally has a low solubility in an organic solvent, it is difficult to form a film by dissolving the compound in the organic solvent to make a solution and then applying the resulting solution on an appropriate substrate. 
     An object of the invention is, therefore, to provide an organic compound which has metallic luster and is stable even in air. 
     Further, another object of the invention is to provide the organic compound which has a high solubility in the organic solvent and consequently is an excellent film-forming material. 
     There is, therefore, a provision of pyrrole derivatives, particularly 2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole derivatives, having the following general formula:                           
     (R represents hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aromatic group, formyl group, an acyl group, an alkoxycarbonyl group, or an alkenyl group.) 
     Moreover, there is a provision of a film-forming material composed of the above pyrrole derivative, and further provision of the present invention is a method of preparing the above derivatives. 
     As mentioned above, some high-molecular weight compounds have been known which have metallic luster. However, no organic low-molecular weight compound has been reported at all which clearly has metallic luster. 
     The inventor has found that the aforementioned low-molecular weight compound which has the specific structure, namely the π-electron conjugated system, in a molecule thereof has a stable metallic luster and good stability in air, and further has a high solubility in common organic solvents and hence is an excellent film-forming material, and then accomplished this invention. 
     The aforementioned compounds having the tricyanoethenyl group show a clear gold color, bronze color or the like in its crystal state or thin film state. Further, nevertheless the compounds can dissolve in the common organic solvents such as acetone, benzene, chloroform, or the like, they can easily precipitate therefrom after dissolving therein. For example, standing of the solution allows metallic colored crystals to precipitate therefrom. 
     Further, by developing, coating, and drying the solution containing the compound in the organic solvent on a surface of an appropriate substrate, a coating film can easily be formed thereon. 
     Since the compounds according to the present invention have a surprisingly high stability against beat, they can be used for formation of a evaporated film. Further, by heating the compound up to not less than its melting point to melt it and then cooling the melt, crystals can be formed. Moreover, the compounds according to the invention can have a stable melting state and also exhibit a relatively high electrical conductivity. 
     Besides, iodine or the like may dope into the compound according to the present invention, for the purpose of enhancing its electrical conductivity. 
     In the aforementioned general formula, R represents hydrogen, a substituted or unsubstituted alkyl or cycloalkyl group, a substituted or unsubstituted aromatic group, formyl group, an acyl group, an alkoxycarbonyl group, or an alkenyl group. Besides, the alkyl or cycloalkyl group constituting R preferably has 1-18 carbon(s) and more preferably 1-12 carbon(s). The substituent for the an alkyl or cycloalkyl group is preferably alkoxy group having 1-18 carbon(s); an aromatic group such as phenyl group, naphthyl group, benzothienyl group, indolyl group, pyridyl group, phenoxy group, naphthyloxy group; or a halogen atom such as bromine, iodine, chlorine, or fluorine. 
     The aromatic group constituting R is preferably phenyl group, naphthyl group, thienyl group, benzothienyl group, indolyl group, pyridyl group or the like. A substituent for the aromatic group is preferably alkyl group having 1-18 carbon(s), more preferable 1-12 carbon(s), alkoxy group having 1-18 carbon(s), more preferable 1-12 carbon(s), phenoxy group, naphthyloxy group, monoalkylamino group, dialkylamino group, thioalkyl group, bromine, iodine, chlorine, fluorine. An alkyl group constituting the monoalkylamino group, the dialkylamino group, or the thioalkyl group has preferably 1-18 carbon(s). 
     The acyl group, the alkoxycarbonyl group, or the alkenyl group constituting R preferably has 1-18 carbon(s), more preferable 1-12 carbon(s). 
     Particularly when R represents alkylphenyl or alkoxyphenyl group having 4-12 carbons of alkyl or alkoxy group, a thin film with metallic luster can be made by spin coating the compound according to the invention on the appropriate substrate. 
     The compound according to the invention can be manufactured by reacting a compound shown by the following general formula with tetracyanoethylene in an organic solvent.                           
     Alternatively, an organic metal compound shown by the following general formula is produced by reacting the above compound with a base such as butyllithium, lithium diisopropylamide or the like.                           
     Subsequently, the reaction of the resulting compound with tetracyanoethylene generates the compound according to the invention. 
     Besides, when R is t-butoxycarbonyl group, heating of the compound according to the invention can bring substitution of R by hydrogen. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawings will be provided by the Patent and Trademark Office upon request and payment of the necessary fee. 
     FIG. 1 is a photograph showing the crystals of the compound in Example 1, 1-[(4-n-hexyloxy)phenyl]-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole. 
     FIG. 2 is a photograph showing the crystals of the compound in Example 20, 1-(2-bromophenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole. 
     FIG. 3 is a photograph showing the crystal of the compound in Example 27, 1-(4-propylphenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole. 
     FIG. 4 is a photograph showing a thin film formed from the bronzy crystals of the compound in Example 9, 1-(4-n-butylphenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be explained in detail below with reference to Examples, but it does not intend to limit the present invention. 
     EXAMPLE 1 
     After dissolving 1-[(4-n-hexyloxy)phenyl]-2,5-bis(2-thienyl)pyrrole (205 mg) into N,N-dimetylformamide (30 ml), tetracyanoethylene (126 mg) was added thereto, and then they were stirred for 24 hours at room temperature. After addition of water thereinto, extraction by toluene was conducted. The obtained organic layer is dried over anhydrous sodium sulfate, and then condensation thereof under vacuum was conducted. Subsequently, the condensed substance is separated by silica gel column chromatography using toluene as eluent to obtain 1-[(4-n-hexyloxy)phenyl]-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole (212 mg, yield 83%). After recrystallization from a chloroform-hexane mixture solvent, crystals having a bronzy metallic luster were obtained. FIG. 1 is a photograph showing the appearance of the crystals. Further, physical properties thereabout are shown bellow. 
     m.p.: 215.2-216.5° C. 
       1 H NMR (CDCl 3 , 300 MHz): δ0.94(3H, t, J=7.0 Hz), 1.35-1.54(6H, m), 1.85(2H, tt, J=7.1 Hz), 4.06(2H, t, J=6.5 Hz), 6.74(1H, d, J=4.4 Hz), 6.86(1H, dd, J=1.1 and 3.8 Hz), 6.90(dd, 1H, J=3.8 and 5.0 Hz), 7.07(d, 1H, J=4.4 Hz), 7.07(d, 2H, J=8.8 Hz), 7.08(d, 1H, J=4.5 Hz), 7.17(dd, 1H, J=1.1 and 5.0 Hz), 7.29(d, 2H, J=8.9 Hz), 7.73(d, 1H, J=4.7 Hz) 
     Infrared absorption spectrum (KBr): 
     2363, 2215, 1655, 1560, 1491, 1362, 1252, 1182 cm −1    
     Ultraviolet-visible absorption spectrum (THF): 
     λmax (ε/M −1 cm −1 ): 328 nm (14000), 624 nm (41000) 
     EXAMPLE 2 
     A solution of 1-(2-isopropyl)-2,5-di(2-thienyl)pyrrole (240 mg, 0.878 mmol) in THF was cooled to −78° C. under nitrogen atmosphere, and then n-butyl lithium (0.6 ml, 1.5M, 0.9 mmol) was dropped thereinto, and subsequently they were stirred for 15 minutes. The obtained solution was dropped into a solution of tetracyanoetylene (342 mg, 1.25 mmol) in THF solution (50 ml) at −78° C., and then they were stirred for 15 minutes. The reaction solution was warmed up to room temperature and stirred for 30 minutes. Then addition of a saturated ammonium chloride aqueous solution (10 ml) thereto stopped the reaction thereon. Further, water (100 ml) was added thereinto, and then three times of extractions by 100 ml of chloroform at each time were conducted. The obtained organic layer was dried by anhydrous sodium sulfate, and then condensation thereof under vacuum was conducted. Subsequently, the condensed substance was separated by a mixture solution (chloroform-bexane=5:1) as eluent in silica gel column chromatography to obtain 1-(2-isopropyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole (219 mg, 0.584 mmol, yield 67%) in crystal state, the crystals had a gold color. Physicochemical properties thereabout are shown bellow. 
     m.p.: 179.0-180.0° C. 
       1 H NMR (CDCl 3 , 300 MHz): δ1.50 (d, 6H, J=7.0 Hz), 4.83 (septet, 1H, J=7.0 Hz), 6.35(d, 1H, J=4.0 Hz), 6.67(d, 1H, J=4.0 Hz), 7.11(dd, 1H, J=3.6 and 5.1 Hz), 7.44(dd, 1H, J=1.4 and 3.6 Hz), 7.27(d, 1H, J=4.4 Hz), 7.44(dd, 1H, J=1.4 and 5.1 Hz), 8.03(d, 1H, J=4.4 Hz) 
     Infrared absorption spectrum (KBr): 
     2210, 1500, 1450, 1430, 1405, 1380, 1355, 1290, 1178, 1105 cm −1    
     Ultraviolet-visible absorption spectrum (THF): 
     λmax (ε/M-1 cm −1 ): 585 nm (39500) 
     EXAMPLES 3-35 
     A compound in each Example shown in FIGS. 1 and 2 was manufactured in the same procedures as Example 1 or 2, and a melting point, appearances,  1 H NMR, and an ultraviolet-visible absorption spectrum thereabout were measured. Among them, Tables 1 and 2 show each substituent R, m.p. and appearances. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Example 
                   
                   
                   
               
               
                 No. 
                 R 
                 m.p. (° C.) 
                 appearance 
               
               
                   
               
             
             
               
                  3 
                 p-CH 3 O—C 6 H 4   
                 219.6-220.4 
                 bronzy crystal 
               
               
                  4 
                 p-C 2 H 5 O—C 6 H 4   
                 201.5-202.4 
                 yellowish gold crystal 
               
               
                  5 
                 p-n-C 4 H 9 O—C 6 H 4   
                 174.5-175.3 
                 bronzy crystal 
               
               
                  6 
                 p-n-C 12 H 25 O—C 6 H 4   
                 153.2-153.6 
                 brown crystal 
               
               
                  7 
                 p-CH 3 —C 6 H 4   
                   222-222.5 
                 gold crystal 
               
               
                  8 
                 m-CH 3 —C 6 H 4   
                 213.5-214 
                 gold crystal 
               
               
                  9 
                 p-n-C 4 H 9 —C 6 H 4   
                 171.5-172.5 
                 bronzy crystal 
               
               
                 10 
                 p-tert-C 4 H 9 —C 6 H 4   
                 235.5-236 
                 gold crystal 
               
               
                 11 
                 p-sec-C 4 H 9 —C 6 H 4   
                   188-189 
                 dull greenish gold 
               
               
                   
                   
                   
                 crystal 
               
               
                 12 
                 p-n-C 6 H 13 —C 6 H 4   
                   156-157 
                 bronzy crystal 
               
               
                 13 
                 p-n-C 12 H 25 —C 6 H 4   
                   138-139 
                 magenta powder 
               
               
                 14 
                 CH 3   
                   209-210 
                 gold crystal 
               
               
                 15 
                 cyclohexyl 
                 186.5-187 
                 auburn crystal 
               
               
                 16 
                 p-F-C 6 H 4   
                 246.2-247 
                 gold crystal 
               
               
                 17 
                 m-F-C 6 H 4   
                 241.5-242.5 
                 greenish gold crystal 
               
               
                 18 
                 o-F-C 6 H 4   
                   225-226 
                 greenish gold crystal 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Example No. 
                 R 
                 m.p. (° C.) 
                 appearance 
               
               
                   
               
             
             
               
                 19 
                 m-Br—C 6 H 4   
                  258-259.5 
                 deep greenish gold 
               
               
                   
                   
                   
                 crystal 
               
               
                 20 
                 o-Br—C 6 H 4   
                   202-202.5 
                 gold crystal 
               
               
                 21 
                 p-Cl—C 6 H 4   
                   245-245.8 
                 gold crystal 
               
               
                 22 
                 m-Cl—C 6 H 4   
                 247.5-248.5 
                 greenish gold crystal 
               
               
                 23 
                 o-Cl—C 6 H 4   
                   188-189 
                 greenish gold crystal 
               
               
                 24 
                 m-I—C 6 H 4   
                 239.2-240 
                 brownish gold crystal 
               
               
                 25 
                 p-Me 2 N—C 6 H 4   
                   252-253 
                 magenta powder 
               
               
                 26 
                 p-tert-C 4 H 9 S—C 6 H 4   
                   206-207 
                 bluish violet crystal 
               
               
                 27 
                 p-n-C 3 H 7 —C 6 H 4   
                   199-200 
                 gold crystal 
               
               
                 28 
                 2,6-(C 2 H 5 ) 2 C 6 H 4   
                 180.5-181.5 
                 gold crystal 
               
               
                 29 
                 3,5-(CH 3 ) 2 C 6 H 4   
                   259-260 
                 blackish green crystal 
               
               
                 30 
                 p-(CH 3 S)C 6 H 4   
                   228-229 
                 copper-colored crystal 
               
               
                 31 
                 3,5-(CH 3 O)C 6 H 4   
                   259-260 
                 blackish green crystal 
               
               
                 32 
                 o-(CH 3 O)C 6 H 4   
                 202.1-202.9 
                 blackish gold crystal 
               
               
                 33 
                 H 
                 ≧300 
                 gold crystal 
               
               
                 34 
                 (CH 3 ) 3 C—OC(═O) 
                 138.5-140 
                 blackish green crystal 
               
               
                 35 
                 CH 2 ═CHCH 2   
                   167-167.5 
                 bronzy crystal 
               
               
                   
               
             
          
         
       
     
     FIG. 2 is a photograph showing crystals of the compound produced in Example 20, 1-(2-bromophenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole, and FIG. 3 is a photograph showing crystals of the compound produced in Example 27, 1-(4-n-propylphenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole. 
     EXAMPLE 36 
     Magenta powder of the compound in Example 13, 1-(4-n-dodecylphenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole was heated to 140-145° C. to melt it, and then cooled it to generate gold colored crystal. 
     EXAMPLE 37 
     A solution of the bronzy crystals of the compound produced in Example 9, 1 -(4-n-butylphenyl)-2-(2-thienyl)-5-(5-tricyanoethenyl-2-thienyl)pyrrole, in chloroform was pored into 200 ml of eggplant type flask. Then the chloroform was evaporated slowly while the flask was rolled. As a result, a bronzy to gold colored thin film was appeared on the inner surface of the bottom of the flask as shown in FIG.  4 .