Methine chain substituted styryl cyanine dyes—part I

METHINE

CHAIN

J. C.

SUBSTITUTED DYES-PART

BANERII. A.

K.

MANDAL

I

STY-RYL CYANlINE

and B. K.

BANERJEE

Department of Chemistry. B. N. College. Porno Uniwrsily. Porno 800005. Bihar. India (Received:

17 June,

1981)

SUMMARY Tbventy-seL-en styryi dyes having I-naphthyi and 2-naphthyi substituenrs at the p-carbon atom (/3- to the heterocyclic moiety) of the methine chain have been prepared by condensing p-diethylaminophenyl2-naphthyl ketone, p-dimethyZaminophenyl /-naphthyl ketone and p-dimethylaminophenyl 2-naphthyl ketone with quaternised salts of variously substituted quinaldines and lepidine. The dyes obtained show hypsochromic shifrs in absorption maxima compared with their anaiogues having no szibstituent in the methine chain wherever comparable data have been available in the Iiterature. The photosensitisation properties of the dyes have also been studied.

1.

INTRODUCTION

Styryi cyanine dyes have been extensively studied’ for their usefulness as photosensitisers. Different heterocyclic bases and diversely substituted h&erocyclic bases have been quatemised with different alkyl iodides and the quaternary salts thus obtained have been used for the preparation of such dyes. The carbonyl component required has also been suitably varied. The dyes obtained by thecondensation of the quaternary salts and the carbonyl components have been studied with respect to their absorption and their photosensitising properties. Though it is reported that substitution in the methine chain, either CY-or fl- (with respect to the heterocyclic moiety), Ieads to hypsochromic shifts in A_X,2V3 this aspect of substitution does not seem to have been thoroughly stud&is4 It was, therefore, considered to be of interest to study inter aiia the effect of such substitution as well as to prepare new j% substituted dyes. For this purpose three ketones, viz. p-dimethylaminophenyl lnaphthyl ketone (Ketone-l), p-dimethylaminophenyl2-naphthyl ketone (Ketone-2) 273 Dyes and Pigmenrs 0143-7208/82/0003-0273/SO2.75 Printed in Great Britain

&?_IApplied

Science

Publishers

Ltd.

England,

1982

274

J. C.

BANERJI,

A.

R.

MANDAL,

B.

K.

BANERJEE

R, \.

xq&cHgR1 I

/\

IR

Dye

R,

A,

CH,

4

CH3

4

CH,

A,

CH3

A,

CH,

4i

CH,

A,

CH,

As

CH3

D_ve

X

R CH, CH,

CH3 CH,

CH,

CH, CH, C2Hs

D,l:e

H CH, Cl Br 1 OCH, 0C2H,

H

X

R

/ X

R

R,

c,

C?_Hs

CH3

H

G

C,Hs

CH3

CH3

c3

C,H,

CH,

C,

C,H,

CM3

C,

C,H,

CH3

G

C,H,

CH3

Cl Br I OCH,

G

GH,

CH3

OC,Hs

G

GH,

GH,

H

X

R

B, Bz

CH,

H

CH,

CH3

CH3

CH,

I 0CH3

%

CH,

CH3

O&H,

B.4

CH3

Cl Bt-

C,H, Fig.

1.

H

METHINE!

CHAIN

SUBSTITUTED

STYRYL

CYANIDE

DYES-PART

I

275

R

Dye

Fig. 1-conrd.

and p-diethylaminophenyl 1-naphthyl ketone (Ketone-3) have been condensed with diversely substituted quinaldine alkyl iodides and lepidine methiodide in boiling ethanol (with piperidine as catalyst) affording /_&naphthyl (/I- &ith respect to the hetero-nucleus) styryl cyanines. The p-diethylaminophenyl I-naphthyl ketone was prepared by the method adopted by Shah ef a2.’ The -dyes under report are characterised in Fig. 1.

2. The absorption A study of conclusions.

RESULTS

AND

CONCLUSIONS

and sensitisation of the dyes are given in Table the absorption maxima of the dyes leads to

1. some

interesting

276

J. C. BANEFXJI,

A.

K. MANDAL, TABLE

&e

2.1.

Remarks

Extended IO (mp)

500 515 510 513 517 505 5og 520

Nil Nil 540 600 600 Nil 560 600

505 522 515 518 525 508 512 529

Nil Nil 600 6”g Nil 600 595

502 518 515 519 524 508 512 528

:: 540 560 560 Nil 605 610

524 535 525

Nil Nil 585

The eHecr of subsiirurion

1 Sensirisarion

L,, hw)

B. K. BANEFUEE

in rhe merhine

Weak sensitisztion Feeble max. at 570pm Uniform Weak sensitisation Feeble max. at 570mp

Weak sensitisalion Weak sensitisation Weak sensitisation Weak sensitisation Weak sensitisation Weak sensitisation Uniform Weak sensitisation Weak sensitisation Weak sensitisation Uniform Uniform

Weak sensitisation chain

The dyes reported have one or other substituent attached to the & (j?- to the heterocyclic component) position of the methine chain. A bulky substituent as in the case here, is likely to hinder sterically the planarity of the resonating system. Such hindrance to resonance may be expected to interfere with the delocalisation of the 7~ molecular orbitals and cause a hypsochromic shift in absorption maxima. Such indeed has been found to be the case--the /?-substituted dyes have shown appreciable hypsochromic shifts in absorption maxima, compared with their unsubstituted analogues (Table 2). It may be pointed out also that bond alternation will exist since the system is not electronically symmetrical and hence crowding substituents will cause hypsochromic shifts owing to rotation about essentially single bonds.6 The earlier observation3 that substitution at the &position of the methine chain of hemicyanines leads to a hypsochromic shift in absorption is thus confirmed. 2.2. Comparison of the efsects /l-position of the methine chain &Chain

substitution

of

I-naphthyl

of I-naphthyl

and 2-naphthyl

and 2-naphthyl

substitution

at the

groups shows an interesting

ME-i-HINE

CHAIN

SUBSTITUTED

STYRYL

CYANIDE

DYES-PART

277

I

TABLE 2 EFFECT OF ~SUW’lTUllON &Subsritured dyes Symbol

Substitution (j3-chain)

fi-Unsubstirured

dyes

Substitution (&choin)

k)

Reference

Hypsochromic shijr (mp)

AI

I-Naphthyl

500

Hydrogen

530

7, 8, 9. 10

30

::

2-Naphthyl 1-Naphthyl

502 505

Hydrogen

7. 8. 119. IO

25 -

G L,

1-Naphthyl 1-Naphthyl

518 524

Hydrogen Hydrogen

Not 530 recorded 556 550

8’“9

38 26

L? 4

2-Naphthyl 1-Naphthyl

535 525

Hydrogen

550 560

8:139

:z

The former in all analogous dyes has caused small but definite bathochromic shifts in absorption (Table 3). This may be attributed to administration of the steric effect in the 2-naphthyl dyes as compared with the I-naphthyl dyes caused by the peri-H. It is also significant that the electron density at the lposition in the naphthyl moiety is greater than that at the 2- position. relationship.

TABLE COMPARISON

p-Naphthyl- 1-dyes B-Naphthyl-2-dyes Bathochromic shift (mp)

2.3.

Lengthening

OF

&,,_

OF

l-

3 AND

i?-NAPHTHYL.

DYES

A, B, 5

of the

conjugared

chaitz

Bathochromic shifts in absorption of cyanine dyes with lengthening of the conjugated chain of carbon atoms between polyvalent atoms involved in the resonance system is an established fact. Using lepidine quaternised salts, a number of dyes have been prepared, wherein the lengthening of the methine chain has been annular. The absorption maxima of these dyes exhibit bathochromic shift in absorption over their quinaldine analogues (Table 4). TABLE EFFECTOF

INCREASE

L,

4 THE

CHAIN

LENGTH

Barhochromic shift (mp)

Dye

Al

IN

500 524

24 30

502 525 >

23

278

J.C.

BANERJI, A. K. MANDAL, B. K. BANERJEE

2.4. The p-diethylamino dyes vis-a-xds their dimethyl analogues T h e p - d i e t h y l a m i n o d y e s s h o w a b a t h o c h r o m i c shift, t h o u g h small, in Area~ c o m p a r e d with their d i m e t h y l a n a l o g u e s ( T a b l e 5), an o b s e r v a t i o n also m a d e b y earlier w o r k e r s 2 a n d p r e s u m a b l y d u e to g r e a t e r e l e c t r o n d o n a t i o n b y the - - N E t 2 g r o u p as c o m p a r e d with the - - N M e z g r o u p l e a d i n g t o a n increase in e l e c t r o n symmetry. TABLE 5 p = D I E T H Y L A N D p - D I B . I E T H Y L ANALOGLIF..S

Dye

).,,~ (rap)

Ai Ct Az Cz

500 ) 502 515 ) 518

A3 Ca

510 ) 515

Bathochromic shift (mla) 2 3 5

2.5. Tile ethiodide dyes vis-a-vis their methiodide analogues T h e e t h i o d i d e d y e s have s h o w n u n i f o r m b a t h o c h r o m i c shifts o f a b o u t 2 0 - 2 6 m/a in 2 ~ over their m e t h i o d i d e a n a l o g u e s ( T a b l e 6). T h e d y e s r e p o r t e d were f o u n d to be w e a k sensitisers. In several cases the e x t r a s e n s i t i s a t i o n was a l m o s t nil. H o w e v e r , t h e d y e s d e r i v e d f r o m q u i n o l i n i u m e t h i o d i d e were f o u n d to possess s o m e e x t r a - s e n s i t i s i n g p r o p e r t y . It c a n t h e r e f o r e be c o n c l u d e d t h a t a n y s u b s t i t u e n t a t the fl-position o f the m e t h i n e c h a i n adversely affects the e x t r a - s e n s i t i s i n g p r o p e r t y o f the dyes. T h i s is, o f c o u r s e , n o t s u r p r i s i n g c o n s i d e r i n g the f a c t t h a t s u c h c h a i n - ( f l - ) s u b s t i t u t e d d y e s a b s o r b a t s h o r t e r w a v e l e n g t h s t h a n their u n s u b s t i t u t e d a n a l o g u e s . B o t h o f these effects are p r o b a b l y c a u s e d by the n o n - p l a n a r i t y o f s u b s t i t u t e d d y e m o l e c u l e s d u e to b u l k y substitution. TABLE 6 I~FHIODIDE A N D M ~ F H I O D I D E DYES

Dye

2,,~

(mu)

Aa A~ Ba BI

.520 ) 500 529 ) 505

c.

528 "L

CI

502 J

Bathochrom ic

shift (mu) 20 24 26

METHlhZ

CHAIN

SUBSTITUTED

3.

STYRYL

CYANIDE

DYES-PART

279

I

EXPERIMENTAL

(All melting and boiling points are uncorrected.) 3.1. Preparatioiz of the ketones p-Diethylaminophenyl I-naphthyl ketone was prepared by utilising the general procedure of Shah et al. ’ It was purified by distillation under reduced pressure (b.p. at 1-5 mm, 235”C, yield 44 “//,)_ Repeated attempts to prepare the oxime, semicarbazone and DNP of this compound were unsuccessful. The ketone, however, readily afforded the styryl derivative which gave the predicted analysis. Ultraviolet peaks at 220 rnp (intense) and at 332 mp (weak) (a&unsaturated ketone). The other two ketones were also prepared by following the procedure adopted by Shah et ai.5

TABLE Symbol

Yield ( “/,)

28.59

Afelling

poh

Molecular

fornmla

(“Cl

7 Found

N

( %)

Cafculared

( %)

Halogen

N

Halogen

19.78 19.25 19.32 2.544 19.23 23.03

ZiO-1 221-2 208 204 205 203 196

C,,H,,N,I C,,H,,N,I C,oHxN,ICl C,,HxN,IBr CmHxNJz CA, H,gN,01 C,,H,,N,OI

5.21 5.06 4.89 4-5s 4.23 4-93 4.69

23-49 22.87 28-25 33-30 38-12 22-26 21-71

5.16 5.03 4.85 4.50 4.19 4.89 4.77

23.43 22-84 28-18 33-33 38.02 22.20 21.67

2

25-18 24-28 19.42

225 202 210

C.,H,,N.I C,,H,,N,ICl C;;H;;N;!

5.19 4.81 5.08

23.48 22.91 28.24

S-16 4.85 503

23.43 28.18 22-84

2

23-34 14.97

249 186

p-$,~*;B

4-24 4.56

38.09 33-11

4-19 4.50

38.02 33.33

5

18.76 19.22

205 190

CxH,,N,OI C;:H:6,N;dI

4.81 4-85

21.72 27.29

4-71 4.89

2i 22.29 .67

C, ::

16.66 19.85 17.29

188 202 180

CxH,,N,I C,,H,,N,ICI C,aH,,N,I

4.95 4.67 4.81

22.32 26.95 21-80

4.91 4.63 4-79

22.28 26.88 21-75

C.

21-81

210

C,,H,oN,IBr

4-36

31-97

4-31

31.90

2 CZ

16.66 14.36 22.96

221 I83 198

C,,H,,N,I, C,,H,,N,OI C~~H~~N~01

4-70 4-08 4-59

36.55 21-23 22-71

4.66 4.02 4.56

36.50 21.16 22-68

A8

21.58

210

Cx,H,,N,I

5.08

22-93

5.03

22-84

2

IS-45 18.83

210 180

C,,H,,N,I C,,H,,Nd

4.76 s-07

22-79 21.79

4.79 5.03

21.75 22-84

I-1

25-83 35.96 26.31

225 230 221-2

C,oH,,N,I CmH,,N,I CaIH,,N,I

5-12 5.18 4-94

23-48 23.53 22-3s

5-16 S-16 4.91

23.43 23-43 22.28

280

3.

C.

BANERJI,

A.

K.

MANDAL,

B.

K.

BANERJEE

plDimethylaminophenyI i-naphthyl ketone: @e yellow crystals, yield 48-5 % (lit.‘, m-p. 115-16”C, yield 35”/@. p-Dimethyiaminophenyf 2-naphthyl ketone: pale yellow crystals, yield 56% (lit.5, m-p. 128-9”C, yield 40 %)_

m-p.

115”C,

m-p.

128 “C,

3.2. General procedure for the preparation of the dyes The ketone and the quatemary salt in molar proportions were dissolved in absolute ethanol (20ml) together with two drops of piperidine and the solution was gently boiled under reflux for 4 h. The solution was concentrated, when a dark viscous mass was obtained. This was repeatedly washed with ether to remove any unchanged ketone and then with boiling water to remove any unchanged quatemary salt. Finally the mass was crystallised from ethyl alcohol_ The yields, m.p.s and the analytical data of the dyes are listed in Table 7.

REFERENCES 121, 946 (1922). I. W. H. MILLS and W. J. POPE, 1. Chem. Sot.. 2. F. M. HAMER. Cyanine dyes and related compounds. p. 398. New York, Interscience Publishers (1964). 3. 1. G. FARBENIND. AG Brit. Patent 498012 (30 June 1937). A. K. MANDAL, Ph.D. Thesis, Patnz University, Patna. India (1978). Z: SHAH er al.. J. Chem. Sot., 642 (1932). 6. J. GRIm-rHs. Colour and consrirurion of organic mokuies. London, Academic Press (1976). 2. 102. 63 (1921). 7. W. KONIG and 0. TFEICHEL. J. Prak. Chem.. 8. 0. BLOCH and F. M. HAMER. Phor. J.. 70. 374 (1930). 9. T. GGATA. Bull. Inn. Phys. tbhem. R&. (?obkyoj.16,.583 (1937). 10. A. KAUFMANN and L. G. VALLE-I-I-E,Ser.. 45. 1736 (1912). 11. M. Q. DOJA and D. PRASAD, J. Indian Chem. Sue.. 20. 153 (1943). 12. S. N. SANYAL. Ph.D. Thesis. University of Bihar, Mmxaffzrpur, India (1966). 13. R. J. N. SAHAY. A. K. SINHA and J. C. BANERJEE,J. fndiun Chem. Sot., 43, 235 (1966).