Spiropyran based composition and application thereof as security tag

Abstract

The present invention discloses the spiropyran compound of formula (I), process for preparation thereof and a composition comprising spiropyran compound of formula (I) on a support, wherein said support selected from polymers such as Poly (ethylene oxide), Polydimethylsiloxane (PDMS), Ethylene propylene diene monomer (EPDM).

Claims

1. A composition comprising 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine) and 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] embedded in polydimethylsiloxane.

2. The composition according to claim 1, wherein said composition is configured to be used as a security tag.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Depicts kinetic study of conversion of merocyanine to spiropyran (a) Absorption spectrum of spiropyaran in PEO thin film. (b) Decay constant of MC to SP (c) First-order plot of photo decoration of MC to SP.

(2) FIG. 2: Depicts change in red, green, and blue component upon irradiation (with SP1).

(3) FIG. 3: Depicts time course evolution of red, blue and green components for SP-1 and SP-10 dyes in PDMS film.

(4) FIG. 4: Spiropyran embedded polypropylene fibre (a), and color changes to blue upon exposure to UV light (365 nm) and reversal to the spiropyran (c, upon exposure to IR light).

(5) FIG. 5: First order kinetic plots to derive the rate constant of the ring closing reaction and half-life period.

DETAILED DESCRIPTION OF THE INVENTION

(6) The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

(7) In the view of above, the present invention provides a spiropyran compound of formula (I), process for preparation thereof and a composition comprising spiropyran compound of formula (I) on a support, wherein said support selected from polymers such as Poly (ethylene oxide), polypropylene (PP), polydimethylsiloxane (PDMS), ethylene propylene diene monomer (EPDM).

(8) In an embodiment, the present invention provides a spiropyran compound of formula (I);

(9) ##STR00003##

(10) Wherein, R.sub.1-R.sub.6 is selected independently from alkyl, alkoxy, substituted alkene, substituted alkenoxy, aldehyde, halides, substituted alcohol or substituted acid, aryl;

(11) R.sub.7 is selected independently from alkyl, substituted alkene, aldehyde, alkyl halides, substituted alcohol, substituted acid or substituted alkenoxy.

(12) In preferred embodiment, said spiropyran compound is selected from 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (SP-1, 1), 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (SP-10, 2), 2-(3,3-dimethyl-6-nitrospiro(chromene-2-2-indolin)-1-yl)ethanol (SP-CH.sub.2CH.sub.2OH, 3) or 1,3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline]-5-carboxylic acid (SP-CO.sub.2H, 4).

(13) ##STR00004##

(14) In another, embodiment, the present invention provides a process for the preparation of compound of formula (I), wherein said process comprising the steps of: (a) N-alkylating the substituted 2,3,3-tetramethyl-3H-indoledene with halogenated compound at temperature in the range of 90 to 120 C. for the period in the range of 16 to 24 hr to afford 2,3,3-tetramethyl-3H-indol-1-ium halide; (b) Stirred the reaction mixture of step (a) in base and solvent at temperature in the range of 25 to 30 C. for the period in the range of 15 to 30 min to afford indolinine compound; (c) Condensing compound of step (b) with nitro salicylaldehyde at temperature in the range of 80 to 90 C. for the period in the range of 6 to 8 hr to afford the corresponding spiropyran compound of formula (I).

(15) In preferred embodiment, said halogenated compound is selected from methyl iodide, 2-bromo ethanol, 1-bromodecane or 3-methyl-2-butanone.

(16) In another preferred embodiment, said solvent is diethyl ether.

(17) In yet another preferred embodiment, said base is sodium hydroxide (NaOH).

(18) In yet another embodiment, the present invention provides a composition comprising a spiropyran compound of formula (I) on a support, wherein said support selected from polymers such as Poly (ethylene oxide), polypropylene (PP), Polydimethylsiloxane (PDMS), Ethylene propylene diene monomer (EPDM).

(19) In preferred embodiment, said spiropyran compound of formula (I) is selected from 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (1), 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2), 2-(3,3-dimethyl-6-nitrospiro(chromene-2-2-indolin)-1-yl)ethanol (3) or 1,3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline]-5-carboxylic acid (4).

(20) In another preferred embodiment, said composition comprises spiropyran compound of formula (I) embedded in polyethylene oxide.

(21) In yet another preferred embodiment, said spiropyran compound of formula (I) is selected from 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (1), 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2), 2-(3,3-dimethyl-6-nitrospiro(chromene-2-2-indolin)-1-yl)ethanol (3) or 1,3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline]-5-carboxylic acid (4).

(22) In still another preferred embodiment, said composition comprises 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2) embedded in polypropylene.

(23) In yet still another preferred embodiment, said composition comprises 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (1), 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2) spiropyran embedded in polydimethylsiloxane.

(24) In yet still another preferred embodiment, the ratio of a spiropyran compound of formula (I) and a support is in the range of 2% of spiropyran:98% of support to 20% of spiropyran:80% of support.

(25) In yet still another preferred embodiment, said composition can be used as a security tag.

(26) The process for the preparation of spiropyran compound of formula (I) is as depicted in scheme A;

(27) ##STR00005##

(28) From FIG. 1 it is observed that the SP-1 (1) embedded PEO film not showed any appreciable absorbance at 560 nm (FIG. 1a, thick line), however upon exposing the film to 365 nm light (1 W LED source) for 10 s, formation of blue colored merocyanine was monitored by the appearance of a broad peak centered at 560 nm, and FIGS. 1b and 1c showed the first order kinetic plot to derive the rate constants and half-life of merocyanine intermediate.

(29) The utilized SP-1(1) embedded PDMS film, a colorless transparent film (FIGS. 2, 1) changes its color to purple color (FIGS. 2, 3), and it is red fluorescent under UV light (365 nm) (FIG. 2. 2) and the colored merocyanine turned to colorless SP-1 within 7 minutes. The bar diagram showed the change in RGB component (RRed, GGreen, BBlue) at each stages, FIG. 1-4. The change in green component is very significant (145 (1)-30 (3)-105 (4) which can be used as a security marker.

(30) The SP-1 (1) and SP-10 (2) are embedded on PDMS and spread over in a A4 sheet so that thin film of SP1@PDMS and SP10@PDMS is formed and cured at 80 C. A time course study of change in RGB component is monitored (FIG. 3).

(31) The SP-10 is melt compounded to polypropylene and fibres of 25 micron diameter is extruded, and change of color change from colorless (FIG. 4a) to purple color (FIG. 4b) is monitored upon exposure to 365 nm for 10 s. The color disappearance is realized by exposing the fibres to IR lamp for 5 s (FIG. 4c). Also the kinetics at room temperature is monitored to arrive a half life of 372 s (FIG. 5).

(32) In one embodiment, the present invention provides a composition of SP-10 in to polypropylene fiber. The spiropyran derivatives is melt compounded into polypropylene, a thermoplastic fibre forming polymer, using a DSM twin screw micro compounder and successfully extruded into fibres of 25-30 micron diameter. The spiropyran derivatives are found to be thermally stable under polymer melt-processing conditions and retained their photochromic function. Interestingly, the time of exposure for inducing color change is considerably reduced when the geometry is changed from films to fibres, owing to higher specific surface area of fibres. Upon exposing the pressed polypropylene film containing SP-10, showed the immediate color change to blue, and the kinetics on the reverse reaction is studied. The kinetic study showed the half life period of 372 s (FIG. 5) for the merocynine form.

(33) The systematic studies showed that the half life of merocyanine that is formed by photo-irradiation of SP derivative could be modulated by proper choice of polymer and the functional groups at the SP. SP embedded polypropylene fiber is formed and studied the photochromic activity of the fiber.

(34) The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

EXAMPLES

Example 1: Synthesis of 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (1)

(35) ##STR00006##

a) Synthesis of 1,2,3,3-tetramethyl-3H-indol-1-ium iodide (6)

(36) 2,3,3-trimethyl indolinine (3 g, 18.8 mmol), methyl iodide (5.35 g, 37.7 mmol) and 80 mL of acetonitrile were heated 110 C. for 8 h. After this period the remaining solution was cooled. It was concentrated with reduced pressure and then it was washed with diethyl ether (330 mL). The yield of compound was show shining pink color solid. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.67 (6H, s, (CH.sub.3)2); J=4.31 (3H, s, (CH.sub.3); J=3.11 (3H, s, NCH.sub.3); J=7.57-7.67 (4H, m).

b) Synthesis of 1,3,3-trimethyl-2-methyleneindolinine (7)

(37) 1,2,3,3-tetramethyl-3H-indol-1-ium iodide (2 g, 6.63 mmol) was dissolved in a stirred 40% of NaOH (60 mL) and diethyl ether (150 mL) was added into the reaction mixture vigorous and stirred at 25-30 C. for 15-30 mis. After this period of time diethyl ether was separated and dried with anhydrous sodium sulphate. It was filtrated and evaporated under reduced pressure. The yield of compound was yellow oil in nature. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.27 (6H, s, (CH.sub.3)2); J=4.31 (3H, s, (CH.sub.3); J=2.96 (3H, s, NCH.sub.3); J=6.44 (1H d, CH); J=6.68 (1H, t, CH); J=6.72-7.18 (2H, m, CH).

c) Synthesis of 1,3,3-trimethyl-6-nitrospiro(chromene-2,2-indolinine (1)

(38) 1,3,3-trimethyl-2-methyleneindolinine (1 g, 57.7 mmol) and 5-nitrosalicylaldehyde were (1.45 g, 86.5 mmol) in ethanol, and then heated to 80 C. under reflux for 8 h. After this period the solution under reduced pressure. It was purified with ethyl acetate (10%) and pet ether (90%). The nature of compound was green solid. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.20 (3H, s, (CH.sub.3); J=1.31 (3H, s, (CH.sub.3); J=2.76 (3H, s, NCH.sub.3); J=5.95 (1H d, CH); J=6.60 (1H, t, CH); J=6.81 (1H, d, CH); J=6.91 (1H, d, CH); J=7.09 (1H, d, CH); J=7.09 (1H, d, CH); J=7.22 (1H, d, (CH).sub.2).

Example 2: Synthesis of 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2)

(39) ##STR00007##

a) Synthesis of 1-decyl-2,3,3-trimethyl-3H-indol-1-ium bromide (10)

(40) 2,3,3-trimethyl indolinine (2 g, 12.561 mmol), 1-bromodecane (3.3 g, 15.0723 mmol) and acetonitrile were heated at 110 C. reflux for 24 h. After the reaction cooled to room temperature and the solution was concentrated under reduced pressure, oil nature of solidified was formed. It was washed with hexane 3 times, filtrated the compound was dark pink color. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent, it was given below (, ppm., J(Hz)): J=0.85 (3H, t, (CH.sub.3); J=1.27, (12H, s, ((CH.sub.2).sub.6); J=1.36 (6H, s, ((CH.sub.3).sub.2); J=1.39 (2H, t, CH.sub.2); J=1.86 (2H, m, CH.sub.2); J=1.39 (3H, s, CH.sub.3); J=7.5 (1H d, CH); J=7.31-7.36 (2H, m, CHCH); J=7.58 (2H, m, CHCH).

b) Synthesis of 1-decyl-3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline] (2)

(41) 1-decyl-2,3,3-trimethyl-3H-indol-1-ium bromide (500 mg, 1.32 mmol), 5-nirosalicylaldehyde (335 mg, 1.5823 mmol), Piperidine (123.36 mg, 1.45 mmol) in ethanol 20 mL was heated to 80 C. reflux under nitrogen gas at 3-4 h. Then it was concentrated with reduced pressure, it was purified by 15% of ethyl acetate and 85% of toluene. The nature compound color is pink solid. It was characterized by .sup.1H-NMR by using DMSO solvent it was given below (, ppm., J(Hz)): J=0.90 (3H, t, (CH.sub.3) J=1.23-1.56 (22H, m, (CH.sub.3).sub.2 (CH.sub.2).sub.8; J=1.86 (2H, m, CH.sub.2); J=3.18 (1H, t, CH.sub.2); J=5.83 (1H d, CH); J=6.86 (1H d, CH); J=6.87-7.19 (5H, m, (CH).sub.5); J=8.03 (2H, m, CHCH)

Example 3: Synthesis of 2-(3,3-dimethyl-6-nitrospiro(chromene-2-2-indolin)-1-yl)ethanol (3)

(42) ##STR00008##

a) Synthesis of 1-(2-hydroxyethyl)-2,3,3-trimethyl-3H-indol-1-ium bromide (8)

(43) 2,3,3-trimethyl indolinine (2 g, 12.561 mmol), 2-bromo ethanol (2.35 mmol) were heated reflux for 24 h. After the reaction cooled to room temperature and the solution was concentrated under reduced pressure, oil nature of solidified was formed. It was washed with hexane 3 times, filtrated the compound was dark pink color. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.65 (6H, s, (CH.sub.3)2); J=3.14, (3H, s, (CH.sub.3); J=4.2 (2H, t, NCH.sub.2); J=4.89 (2H, t, CH.sub.2); J=7.5 (1H d, CH); J=6.72-7.18 (3H, m, CHCHCH)

b) Synthesis of 9,9,9a-trimethyl-2,3,9,9a-tetrahydrooxazolo(3,2-a)indole (9)

(44) 1-(2-hydroxyethyl)-2,3,3-trimethyl-3H-indol-1-ium bromide (500 mg, 3.51 mmol) was dissolved in 20% of KOH (0.6 g, 10.69 mmol) in water (50 mL) and stirred at 25 C. for 15 mins. Then it was extracted with diethyl ether. The organic layer was concentrated under reduced pressure. The compound nature was yellow in oil. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.26 (3H, s, (CH.sub.3); J=3.29, (3H, s, (CH.sub.3); J=3.29, (3H, s, (CH.sub.3); J=3.52-3.85 (4H, m, CH.sub.2CH.sub.2); J=4.89 (2H, t, CH.sub.2); J=6.77 (1H d, CH); J=6.92 (1H, t, CH); J=7.05-7.14 (2H, m, (CH).sub.2)

c) Synthesis of 2-(3,3-dimethyl-6-nitrospiro(chromene-2-2-indolin)-1-yl)ethanol (3)

(45) 9,9,9a-trimethyl-2,3,9,9a-tetrahydrooxazolo(3,2-a)indole (500 mg, 2.462 mmol) and 5-nirosalicylaldehyde (783 mg, 3.7 mmol) in ethanol 20 mL was heated reflux under nitrogen gas at 3 h. Then it was concentrated with reduced pressure, it was purified by 90% of ethyl acetate and 10% of Methanol. The nature compound color is purple solid. It was characterized by .sup.1H-NMR by using CDCl.sub.3 solvent it was given below (, ppm., J(Hz)): J=1.20 (3H, s, (CH.sub.3); J=1.26 (3H, s, (CH.sub.3); J=3.40 (2H, t, NCH.sub.2); J=3.8 (2H, t, CH.sub.2); J=5.92 (1H d, CH); J=6.92 (1H, t, CH); J=6.70 (2H, q, CHCH); J=6.95 (2H, t, CHCH); J=7.20 (2H, q, CHCH); J=8.06 (2H, d, (CH).sub.2)

Example 4: Synthesis of 1,3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline]-5-carboxylic acid (4)

a) Synthesis of 2,3,3-trimethyl-3H-indole-5-carboxylic acid (12)

(46) 4-hydrazinobenzoic acid (4 g, 21.21 mmol), 3-methyl-2-butanone (3.65 g 42.41 mmol) were dissolved in acetic acid 50 mL. Then it was heated refluxed for 16 h. After that reaction mixture was cooled to room temperature, acetic acid was removed by rotvapor. Then unsaturated solution of potassium carbonate was added, pH=4 level is maintained for adding of HCL and it was extracted with DCM, dried (Na.sub.2SO.sub.4) and concentrated under reduced pressure. The nature compound of the compound is brown solid. It was characterized by .sup.1H-NMR by using DMSO solvent it was given below (, ppm., J(Hz)): J=1.38 (6H, s, ((CH.sub.3).sub.2); J=2.39 (3H, s, CH.sub.3); J=7.7 (1H, d, CH); J=8.17-8.13 (2H, d, (CH).sub.2)

b) Synthesis of 5-carboxy-1,2,3,3-tetramethyl-3H-indol-1-ium iodide (13)

(47) 2,3,3-trimethyl-3H-indole-5-carboxylic acid (1.5 g, 7.3808), methyl iodide (2.1 g, 14.76 mmol) in acetonitrile 60 mL refluxed for 14 h. After that reaction mixture was cooled to room temperature, acetonitrile was removed by rotvapor. It was washed with diethyl ether and filtrated, the compound was brown solid. It was characterized by .sup.1H-NMR by using DMSO solvent it was given below (, ppm., J(Hz)): J=1.56 (6H, s, ((CH.sub.3).sub.2); J=3.99 (3H, s, CH.sub.3); J=2.81 (3H, s, NCH.sub.3); J=8.03 (1H, d, CH); J=8.20 (1H, d, CH); J=8.38 (1H, t, CH)

c) Synthesis of 1,3,3-trimethyl-6-nitrospiro[chromene-2,2-indoline]-5-carboxylic acid (4)

(48) 5-carboxy-1,2,3,3-tetramethyl-3H-indol-1-ium iodide (200 mg, 0.5794 mmol), 5-nirosalicylaldehyde (210 mg, 0.9850 mmol), Piperidine (123.36 mg, 1.44875 mmol) in ethanol 20 mL was heated reflux under nitrogen gas at 6 h. Then it was concentrated with reduced pressure, it was purified by 10% of ethyl acetate and 90% of toluene. The nature compound color is yellow solid. Then characterized by .sup.1H-NMR, it was some impurities there. So once again it was purified with 20% of ethyl acetate and 80% of pet ether. It was characterized by .sup.1H-NMR by using DMSO solvent it was given below (, ppm., J(Hz)): J=1.19 (3H, s, (CH.sub.3); J=1.27 (3H, s, (CH.sub.3); J=2.79 (3H, s, NCH.sub.3); J=6.07 (1H d, CH); J=6.75 (1H d, CH); J=7.31 (1H d, CH); J=7.70 (1H d, CH); J=7.82 (1H d, CH); J=8.07 (1H d, CH); J=8.28 (1H d, CH)

Example 5: Kinetic Experiment for Spiropyran Thin Film

(49) Spiropyran in Polyethylene Oxide Thin Film

(50) 2 mg of spiropyran was dissolved in 4 mL of 0.2% PEO (in chloroform). Thin film was formed by adding 0.5 mL of polymer solution to a clean quartz plate which was kept on the spin coater. Then washed quartz plate was kept in spin coater instrument, the film was dried at room temperature for 15 mins. The kinetics of merocyanine to spiropyran was monitored by UV-Vis spectroscopy (color to colorless) by observing the absorbance of merocyanine. The change in absorbance with respect to time is monitored and evaluated the first order kinetic constant (FIG. 1; a, b, c). The kinetic data for the spiropyran derivative 1-4 in four different polymers is provided in Table 2.

(51) Formula:

(52) Calculate the rate constant
kt=ln(A.sub.0A.sub.a/A.sub.tA.sub.a) A.sub.0=Initial absorption @ max nm (Merocyanine) A.sub.a=Final absorption @ max nm (Spiropyran) A.sub.t=absorption at a given time Half life time
t.sub.1/2=0.693/kt

(53) Kinetic data of other spiropyran and polymer matrix is also calculated this way table is given below;

(54) TABLE-US-00001 TABLE 2 The kinetic data for the spiropyran derivative 1-4 in four different polymers SP-1 SP-10 SP-CH.sub.2CH.sub.2OH SP-CO.sub.2H.sup.a Rate Rate Rate Rate Polymer/ constant constant constant constant concentration (s.sup.1) at rt (s.sup.1) at rt t.sub.1/2 (s.sup.1) at rt t.sub.1/2 (s.sup.1) at rt (% wt) k.sub.MC.fwdarw.SP t.sub.1/2 (s) k.sub.MC.fwdarw.SP (s) k.sub.MC.fwdarw.SP (s) k.sub.MC.fwdarw.SP t.sub.1/2 (s) PEO 8 mg 3.5 10.sup.3 199 3.7 10.sup.3 186 8.8 10.sup.4 788 2.6 10.sup.2 27 PDMS 8 mg 6.4 10.sup.3 108 1.1 10.sup.2 61 5.9 10.sup.4 117 EPDM 8 mg 9.5 10.sup.4 725 3.5 10.sup.3 198 1.4 10.sup.3 502 PS 8 mg 2.1 10.sup.3 332 2.9 10.sup.3 237 4.2 10.sup.3 167 .sup.aDue to solubility of this spiropyran probe, the experiments in PDMS, EPDM, and PS is not carried out.

Example 6: Spiropyran in PDMS Polymer

(55) Change in red, green, and blue component upon irradiation is monitored for the SP dye in PDMS film. Systematic kinetic studies in polymers such as PEO, PDMS, EPDM and PS showed polarity dependent effects, in which non-polar polymer showed relatively faster kinetics than the polar polymers. It is interesting to that merocyanine from compound 4 exhibits 100 times higher half-life period in PS than PEO. These remarkable changes in the kinetics may be utilized to make a SP based security tags. In an example, spiropyran embedded PDMS film was exposed to UV light and red, green, blue components of the observed merocyanine color were monitored at each stage of irradiation and at different times. Temperature effect on the ring closing reaction (merocyanine to spiropyran) was also studied and as summarized in Table 3.

(56) ##STR00009##

(57) TABLE-US-00002 TABLE 3 Temperature effect of Merocyanine to Spiropyran (SP-1) in PDMS film Temperature Time (S) 40 C. 39 50 C. 34 60 C. 17 70 C. 11 80 C. 9

Example 7: Embedding SP-10 in to Polypropylene Fiber

(58) Polymer fibres containing spiropyran derivatives could be a suitable platform to realize photochromic features as security threads in currency notes. Hence, inventors also made an attempt to embed photochromic molecules into polymers and make stimuli-responsive fibres. A very small amount of spiropyran derivatives was melt compounded into polypropylene, a thermoplastic fibre forming polymer, using a DSM twin screw micro compounder and successfully extruded into fibres of 25-30 micron diameter. The spiropyran derivatives were found to be thermally stable under polymer melt-processing conditions and retained their photochromic function. Interestingly, the time of exposure for inducing color change is considerably reduced when the geometry is changed from films to fibres, owing to higher specific surface area of fibres. Upon exposing the pressed polypropylene film containing SP-10, showed the immediate color change to blue, and the kinetics on the reverse reaction is studied. The kinetic study showed the half life period of 372 s for the merocynine form. The systematic studies showed that the half life of merocyanine that was formed by photo-irradiation of SP derivative could be modulated by proper choice of polymer and the functional groups at the SP. SP embedded polypropylene fiber was formed and studied the photochromic activity of the fiber.

ADVANTAGES OF INVENTION

(59) a. Novel compounds which can be used for security tags.

(60) b. Novel compounds with lesser reversal time