DE1539930C - Saturable absorbers in Q switches in laser technology - Google Patents

Description

The. The invention relates to saturable absorbers in Q-holders for laser technology.

At least since 1961 it has been known that a giant laser pulse can be generated by emitting rays during excitation of a laser rod is suppressed until an usually high population inversion is built up. If then eliminating the cause of the suppression, the laser immediately emits rays that are considerable have higher energy than ordinary laser beams. These so-called Q-switches in laser technology are for example from British patent specification 953 721 and from the book by J.R. Singer, "Advances in Quantum Electronics", Columbia University Press, 1961, pp. 334-341.

From the journal "Journal of Applied Physics", Vol. 35, No. 8, pp. 2349-2350 (August 1964), as well as from the article by P. P. Sο rο k i η et al, “Ruby Laser Q-Switching Elements Using Phthalocyanine Molecules in Solution "published in the IBM Journal, Vol. 8, No. 2, April 1964, pp. 182 to 184, it is also known to use dyes as saturable absorbers in such automatic Q-switches can be. This procedure produces a saturable dye with an absorption peak placed in the wavelength of the laser beam between the reflectors of an optical resonator, whereby the energy output of the laser is absorbed and the emission of rays is prevented until a sufficiently large population inversion has been achieved by the excitation. At a The incipient laser radiation saturates points above the normal energy threshold of the laser rod the dye, makes it transparent and enables the emission of laser beams in one Giant flash, while the laser in the absence of the saturable dye is already at a lower level Occupation inversion emits rays of lower energy. That is, using one Q-switch in laser technology enables higher peak discharge surges to be achieved than without it Use of a Q-switch are possible. By using a saturable absorber, i. H. one saturable dye, automatic switching is enabled.

In order to be suitable for a Q-switch in laser technology, the dye used as a saturable absorber must not only have an absorption peak at the wavelength of the emitted laser radiation, but the dye must also have a sufficiently short saturation time to become transparent quickly enough , so that an unhindered emission of radiation is possible. If laser beams are to be emitted repeatedly, the saturable dye must have some resistance to permanent fading.
Various dyes which can be used as saturable absorbers are already known which have an absorption peak around 1.06 micrometers, ie the wavelength of the radiation from a laser rod doped with neodymium ions (see e.g.

"Zeitschrift für Naturforschung", Vol. 19 a, No. 7/8, pp. 1019 to 1020 [1964], "Zeitschrift für Naturforschung", Vol. 20a, No. 5, p. 698 [May 1965], "Nature", Vol. 204, No. 4955, p. 276 [17. October 1964], "Journal of Applied Physics", Vol. 35, No. 8, pp. 2349 to 2350 [August 1964], and "IBM Journal", Vol. 8, No. 2, pp. 182 to 184 [April 1964]), but these dyes have the disadvantage that the for such dyes characteristic long chains easily broken under the action of laser radiation both with normal radiation and with excitation of the laser.

The object of the invention is now to specify saturable absorbers in Q-switches with dyes, which do not have the disadvantages outlined above and in particular not only have an absorption peak at the wavelength of a laser, especially one doped with neodymium ions Laser rod, emitted radiation, but which also have a sufficiently short saturation time have to become transparent quickly enough so that unhindered radiation emission is possible and which are also more resistant to permanent fading than those previously known Dyes.

It has now been found that this object can be achieved by using laser technology in Q switches as a saturable absorber certain pyrylium dyes are used, which are composed of an anion a strong acid and one of the cations given below.

The invention accordingly relates to saturable absorbers in Q-switches in laser technology, which are characterized in that the following pyrylium dyes are used, which are composed of an anion a strong acid and one of the following cations:

8 - [5 - (6,7 - dihydro - 2,4 - diphenyl -5 H-1 -benzopyran - 8 - yl) - 2,4 - pentadienylidene] - 5,6,7,8 - tetrahydro-2,4-diphenyl-1-benzopyrylium

8 - [5 - (9,10 - dihydro - 11H - benzo [a] xanthene-8-yl) -2,4-pentadienylidene] -8,9,10,1 1-tetrahydrobenzo [a] xanthylium

8 - [6 - (4,6 - Diphenyl - 2H - pyran - 2 - ylidene) -2.4 - hexadienylidene] - 5,6,7,8 - tetrahydro - 2,4 - diphenyl-1 -benzopyrylium

8 - [5 - (5,6 - dihydro - 2,4 - diphenylcyclopenta- [b] pyran-7-yl) -2,4-pentadienylidene] -5,6,7,8-tetra- hydro-2,4-diphenyl-1-benzopyrylium

~ 8 - [5 - (6,7 - dihydro - 6 - methyl - 2,4 - diphenyl-5 H -1 - benzopyran - 8 - yl) - 2,4 - pentadienylidene] -5,6,7,8 - tetrahydro - 6 - methyl - 2,4 - diphenyl- _1-benzopyrylium

8 - [5 - (6 - cyclohexyl - 6.7 - dihydro - 2,4 - diphenyl-

5 H -1 - benzopyran - 8 - yl) - 2,4 - pentadienylidene] -

6 - cyclohexyl - 5,6,7,8 - tetrahydro - 2,4 - diphenyl-1-benzopyrylium

"8 - {5 - [2,4 - di - (4 - pentyloxyphenyl) - 6,7 - dihydro-5H- benzopyran-8-yl] -2,4-pentadienylidene} -2,4-di- (4-pentyloxyphenyl) -5,6,7,8-tetrahydro-J -benzopyrylium

40

45

55

60 8 - {5 - [2,4 - di - (4 - pentyloxyphenyl) - 6,7 - dihydro-5 H -1 - benzopyran - 8 - yl] - 2,4 - pentadienylidene} -5,6,7, 8-tetrahydro-2,4-diphenyl-1-benzopyrylium

"8 - [5 - (6 - tert - butyl - 6,7 - dihydro - 2,4 - diphenyl-"

5 H -1 - benzopyran - 8 - yl) - 2,4 - pentadienylidene] -

6 - tert. - butyl - 5,6,7,8 - tetrahydro - 2,4 - diphenyl-
1 -benzopyrylium

8 - [5 - (6 - cyclohexyl - 6,7 - dihydro - 2,4 - diphenyl- "
5 H -1 - benzopyran - 8 - yl) - 2,4 - pentadienylidene] -2,4 - di - (4 - pentyloxyphenyl) - 5,6,7,8 - tetrahydro-
_1 -benzopyrylium

8 - [5 - (6,7 - dihydro - 2,4 - diphenyl - 5 H -1 - benzothiopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro-2,4 -diphenyl-1-benzo thiapyrylium

8 - [5 - (6,7 - dihydro - 2,4 - diphenyl - 5 H -1 - benzopyran - 8 - yl) - 2,4 - pentadienylidene] - 5,6,7,8 - tetrahydro-2,4-diphenyl-1 -benzo thiapyrylium

According to a preferred embodiment, the anion is that used according to the invention Pyrylium dyes around a perchlorate anion.

The polymethine pyrylium dyes used according to the invention and of the structure indicated above have opposite known, structurally similar polymethine dyes, for example opposite known polymethine cyanine dyes, an unexpectedly large bathochromic shift of the Absorption maximum. They have an absorption peak at a wavelength of about 1.06 micrometers and can be used repeatedly as saturable absorbers in a neodymium laser without that a substantial permanent bleaching occurs. This is presumably due to that the invention used as a saturable absorber for Q-switches in laser technology Pyrylium dyes are resistant to repeated exposure to laser beams, with the The characteristic degradation of the long chains occurring under the action of the dyes used up to now the laser radiation does not enter.

The pyrylium dyes used according to the invention as saturable absorbers in the claimed Q-switches can be made by a two-step process, in which the first Stage equimolar amounts of a corresponding pyrylium salt with a condensed saturated one Ring with a compound of the formula

[C ₆ H ₅ NH® = CH - (CH = CH) ₁₇₁ NHC ₆ H ₅ ] C1 ⁹

where m = 1 or 2, are reacted, an intermediate product with only one terminal pyrylium ring structure on the methine chain being formed. The saturated, fused-on ring clearly stabilizes the pyrylium ring of the intermediate product. The intermediate product can then be reacted either with another pyrylium salt with a fused ring or with a pyrylium salt with an active methyl group in place of the fused ring to give the desired pyrylium dyes. Such a process is explained in more detail below in the description of the preparation of the dyes 4, 8, 10 and 12.

The thiapyrylium dyes used according to the invention can be prepared in the same way as the corresponding pyrylium dyes using thiapyrylium salts instead of pyrylium salts. The manufacture of a thiapyrylium paint

substance is described below in connection with dye 11 described in more detail.

The preparation of the dyes which can be used according to the invention is described in more detail below will:

dye

8- [5- (6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro-2,4- diphenyl

1 -benzo pyrylium perchlorate

C _ft H

₆ H ₅

C _ft H,

CH-CH = CH-CH = CH

Ce H ₅ λ χ \

ClQf

A mixture of 3.9 g of 2,4-diphenyl-5,6,7,8-tetra-20 2.4 g of the dye in the form of a solid brown hydrobenzo [b] pyrylium perchlorate, 1.4 g of glutacone mass with a receive melting point of 26O ⁰ C, aldehyddianilhydrochlorid, 0.8 g of sodium acetate and 100 ml of acetic anhydride was heated at reflux for 10 minutes. After cooling, the resulting precipitate was filtered off and poured into boiling acetonitrile. The resulting hot mixture was then filtered. There were

Analysis for C ₄₇ H ₃₉ ClO ₆ :

Calculated ... C 76.9, H 5.3, Cl 4.8, 1 g ^ g ^
found .... C 76.8, H 5.2, Cl 4.8 J _{per cent}

dye

8- [5- (9,10-Dihydro-IIH-benzo [a] xanthene-8-yl) -2,4-pentadienylidene] -8,9,10, II-tetrahydrobenzo [a] -

xanthylium perchlorate

CH-CH = CH-CH = CH

obtained substance in the form of a brown solid mass with a melting point of 240 ⁰ C.

A mixture consisting of 3.4 g of benzo [a] -8,9,10,11-tetrahydroxanthylium perchlorate, 1.4 g of glutaconaldehyde dianil hydrochloride, 0.8 g of sodium acetate and 100 ml of acetic anhydride was analyzed for C ₃₉ H ₃₁ ClO for 10 minutes 45 ₆ : heated to reflux temperature for a long time. The fancy, n «,

solid precipitate was filtered off, washed with water and calculated ... C 74.3, H 4.9, Cl 5.6; then washed with acetone. 2.1 g of dye were found: C 74.7, H 5.2, Cl 5.6.

dye

8- [6- (4,6-diphenyl-2H-pyran-2-ylidene) -2,4-hexadienylidene] -5,6,7,8-tetrahydro-2,4-diphenyl-

1 -benzo pyrylium perchlorate

C ₆ H ₅

C _n H

CH - CH = CH - CH = CH - CH

C _fi H,

ClO ₄ ⁹

A mixture of 2.0 g of 2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate and 1.4 g of 1-anilino-5-phenylimino-1,3-pentadiene hydrochloride in 25 ml of acetic anhydride was on return for 15 minutes - _X heated to flow temperature. The blue solution was cooled to a few degrees below boiling temperature, whereupon 1.8 g of 6-methyl-2,4-diphenylpyrylium perchlorate and 0.5 g of sodium acetate were added. The reaction mixture was then heated to reflux temperature until the blue color disappeared, whereupon the mixture was cooled and the precipitate which had separated out was filtered off. The nie

the impact was taken up in boiling acetonitrile, the impurities going into solution. The hot mixture was then filtered. The dye forming the filter residue had one Melting point of 248 ° C.

Dye 4

Analysis for C ₄₄ H ₃₅ ClO ₆ :

Calculated ... C 76.2, H 5.1, Cl 5.1; found .... C 75.9, H 5.2, Cl 4.8.

8- [5- (5,6-dihydro-2,4-diphenylcyclopenta [b] pyran-7-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro-

2,4-diphenyl-1-benzopyrylium perchlorate

C _fi H

CH-CH = CH-CH = CH

C ₆ H ₅

CIO, ®

A mixture consisting of 2.0 g of 2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate and 1.4 g of 1-anilino-5-phenylimino-1,3-pentadiene hydrochloride in 25 ml of acetic anhydride was heated to reflux temperature for 15 minutes. The blue solution was then cooled to a few degrees below boiling temperature, whereupon 1.9 g of 2,4-diphenyl-6,7-dihydro-5 H-cyclopenta [b] pyrylium perchlorate of the formula

C ₆ H ₅

and 0.5 g of sodium acetate were added. The reaction mixture was heated to reflux temperature until the blue color disappeared, whereupon the mixture was cooled and the precipitate which had separated out was filtered off. The filtered precipitate was then taken up in boiling acetonitrile in order to remove the impurities adhering to the dye. The hot mixture was then filtered. The dye obtained as filter residue had a melting point of 255 ^° C.

ClO ₄ Q

Analysis for C ₄₆ H ₃₇ ClO ₆ :

Calculated ... C 76.7, H 5.1, Cl 4.9; found .... C 76.4, H 5.2, Cl 4.8.

Dye 5

8- [5- (6,7-dihydro-6-methyl-2,4-diphenyl-5H-1-benzopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro- 6-methyl-2,4-diphenyl-l -benzopyrylium perchlorate

C _n H

C ₆ H ₅

C _ft H _s

CH ₁

CH-CH = CH-CH = CH

C ₆ H ₅

ClO ₄ ³

A mixture consisting of 4.0 g of 2,4-diphenyl filtered. The filter residue consisted of the ero-methyl-S ^ J.S-tetrahydrobenzopyrylium perchlorate, wanted dye that has a melting point of

1.4g of 1-anilino-5-phenylimino-1,3-pentadiene hydro- 50 possessed from 241 to 243 ° C, chloride, 0.8 g sodium acetate and 100 ml acetic acid

. anhydride, was heated to reflux temperature analysis for C ₄₉ H ₄₂ ClO ₆ : temperature for 10 minutes and then cooled. The fancy, rni HS7 rui;

solid precipitate was filtered off and calculated in boiling ... L //, l, H3, / ,. U4, ();

Acetonitrile added. The hot mix was found C 77.1, H 6.0, Cl 4.5.

Dye 6

C ₆ H ₅

6-cyclohexyl-5,6,7,8-tetrahydro-2,4-diphenyl-1-benzopyrylium perchlorate

C ₆ H ₅

CH-CH = CH-CH = CH

ClO ₄ Q

• A mixture consisting of 4.5 g of 6-cyclohexyl-2,4 - diphenyl - 5,6,7,8 - tetrahydrobenzopyrylium perchlorate, 1.4 g 1 - anilino - 5 - phenylimino -1,3 - pentadiene hydrochloride, 0.8 g of sodium acetate and 100 ml of acetic anhydride, was refluxed for 10 minutes heated and then cooled. The solid precipitated precipitate was filtered off and taken up in boiling acetonitrile. The hot one

10

The reaction mixture was then filtered. The filtered dye had a melting point of 242 ° C.

Analysis for C ₅₉ H ₅₉ ClO ₆ :

Calculated ... C 78.7, H 6.6, Cl 3.9; found .... C 78.4, H 6.8, Cl 4.0.

dye

8- {5- [2,4-Di- (4-pentyloxyphenyl) -6,7-dihydro-5H-1-benzopyran-8-yl] -2,4-pentadienylidene} -2,4-di- (4th pentyloxyphenyl) -5,6,7,8-tetrahydro-1-benzopyrylium perchlorate

.C ₅ H ₁₁ O

OC ₆ H ₁₁

CH-CH = CH-CH =

OC, H,

ClOP

A mixture consisting of 5.58 g of 2,4-di- (4-pen- 30 dendem acetonitrile added. The hot Mityloxyphenyl) - 5,6,7,8 - tetrahydrobenzopyrylium liquor was then filtered. The filtered color chlorate, 1.4 g 1 - anilino - 5 - phenylimino -1,3 - pentadiene hydrochloride, 0.8 g sodium acetate and 100 ml. Acetic anhydride, was refluxed for 10 minutes heated and then cooled. The solid reaction product was filtered off and into it

substance had a melting point of 200 to 201 ⁰ C. Analysis for C ₆₇ H ₇₉ ClO ₁₀ :
Calculated ... C 74.6, H 7.3;

found .... C 74.2, H 7.0.

dye

- {5- [2,4-Di- (4-pentyloxyphenyl) -6,7-dihydro-5H-1-benzopyran-8-yl] -2,4-pentadienylidene} -5,6,7,8-tetrahydro -2,4-diphenyl-l -benzopyrylium perchlorate

C _fi H

C ₆ H ₅

CH-CH = CH-CH = CH

OCH ₁

C1O ₄ ®

A mixture consisting of 2.0 g of 2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate and 1.4 g of 1-anilino-5-phenylimino-1,3-pentadiene hydrochloride in 25 ml of acetic anhydride, was heated to reflux temperature for 15 minutes. The blue solution was then cooled to a few degrees below the boiling temperature, whereupon 3.0 g of 2,4-di- (4-pentyloxyphenyl) - 5,6,7,8 - tetrahydrobenzopyrylium perchlorate and 0.5 g of sodium acetate were added. The reaction mixture was then heated to reflux temperature until the blue color disappeared was. The mixture was then quenched and the solid precipitate formed was filtered off and taken up in boiling acetonitrile. The hot mixture was then filtered. The residue consisted of the dye, which had a melting point of 243 to 244 ° C.

Analysis for C ₅₇ H ₅₉ ClO ₈ :

Calculated ... C 74.8, H 6.5; found .... C 74.9, H 6.7.

dye

S-tXo-tert.-Butyl-oJ-dihydro ^ -diphenyl-SH-l-benzopyran-S-yO ^ -pentadienylidenj-o-tert.-butyl-5,6,7,8-tetrahydro-2,4- diphenyl-l -benzopyrylium perchlorate

A mixture consisting of 4.2 g of 2,4-diphenyl-6 - tert. - butyl - 5,6,7,8 - tetrahydrobenzopyrylium perchlorate, 1.4 g 1 - anilino - 5 - phenylimino -1,3 - pentadiene hydrochloride, 0.8 g of sodium acetate and 100 ml of acetic anhydride, was refluxed for 10 minutes heated. The mixture was then quenched, whereupon the precipitated solid Precipitate was filtered off. The precipitate was then taken up in boiling acetonitrile. The hot mixture was filtered. The filter residue consisted of the desired dye, the had a melting point of 234 ° C.

Analysis for C ₅₅ H ₅₅ ClO ₆ :.

Calculated ... C 77.9, H 6.5, Cl 4.2;
found .... C 78.1, H 6.4, Cl 4.1.

dye

8- [5- (6-Cyclohexyl-6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) -2,4-pentadienylidene] -2,4-di- (4-pentyloxyphenyl ) -5,6,7,8-tetrahydro-1-benzopyrylium perchlorate

A mixture consisting of 2.8 g of 2,4-di- (4-pentyloxyphenyl) -5,6,7,8-tetrahydrobenzopyrylium perchlorate and 1.4 g of 1 - anilino - 5 - phenylimino-1,3-pentadiene hydrochloride and 25 ml of acetic anhydride, was refluxed for 15 minutes. The resulting blue solution was then cooled to a few degrees below the boiling temperature, whereupon 2.3 g of 6-cyclohexyl-2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate and 0.5 g of sodium acetate was added. The reaction mixture was then refluxed for so long heated until the blue color was gone. The mixture was then quenched, whereupon the precipitated reaction product was filtered off and then taken up with boiling acetonitrile. The hot mixture was then filtered. The filtered dye had a melting point of 203 to 204 ° C.

Analysis for C ₃₆ H ₆₇ ClO ₈ :

Calculated ... C 76.4, H 6.8;
found C 76.1, H 6.5.

dye

8- [5- (6,7-dihydro-2,4-diphenyl-5H-1-benzothiopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro-

2,4-diphenyl-1-benzothiapyrylium perchlorate

C _fi H

6 ** 5

CH-CH = CH-CH = CH C ₆ H ₅

Part A

A solution of 10 g of sodium sulfide in 75 ml of water was added to a suspension of 10 g of 2,4-diphenyl-5,6,7,8-tetrahydrobenzo [b] pyrylium perchlorate in 200 ml of acetone. The solution was stirred for 15 minutes after which the reaction mixture was made strongly acidic by the addition of 20% perchloric acid. Stirring was then continued for 1 hour. The resulting solid precipitate was filtered off, washed with water and then recrystallized from ethanol. There were 8 g of 2,4 - diphenyl - 5,6,7,8 - tetrahydrobenzo [b] thiapyryliumperchlorat obtained with a melting point of 168-169 ⁰ C.

Analysis for C ₂₁ H ₁₉ ClO ₄ S:

Calculated ... C 62.7, H 4.7, S 8.0;
found .... C 62.6, H 4.5, S 7.8.

65

Part B ₀

A mixture consisting of 0.5 g thiapyrylium salt, prepared as described under Part A, 0.35 g of 1-anilino-5-phenylimino-1,3-pen tadiene hydrochloride and 15 ml of acetic anhydride, was added for 16 minutes heated to reflux temperature. The blue solution was then allowed to cool a little, followed by more 0.5 g of thiapyrylium salt and 0.2 g of sodium acetate were added. The color of the reaction mixture immediately turned to Braun. The reaction mixture was then allowed to cool, whereupon the solid brown precipitate was filtered off, washed with water and recrystallized from ethanol. There were 0.5 g of the desired dye with a melting point of 247 ° C (with decomposition) receive.

Analysis for C ₄₇ H ₃₉ ClO ₄ S ₂ :

Calculated ... C 73.4, H 5.1, S 8.3;
found .... C 73.2, H 5.3, S 8.1.

dye

2,4-diphenyl-1-benzothiapyrylium perchlorate

C ₆ H ₅

C _fi H,

CH-CH = CH-CH = CH ciop

A mixture consisting of 1.9 g of 2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate, 1.4 g of 1-anilino-5-phenylimino-1,3-pentadiene hydrochloride and 25 ml of acetic anhydride was used for 15 minutes heated to reflux temperature for a long time. The blue solution was then cooled gently and 2 grams of the thiapyrylium salt described in Part A of Dye 11 and 0.5 grams of sodium acetate were added. After thorough mixing, the reaction mixture was cooled, whereupon the resulting yellow-brown solid precipitate was filtered off and then washed with water and finally with ethanol. 1.7 g of dye with a melting point of 249 ^° C. were obtained.

Analysis for C ₄₇ H ₃₈ ClO ₅ S:

Calculated ... C 75.2, H 5.2, S 4.3;
found .... C 75.3, H 5.4, S 4.0.

The table below shows the absorption maxima in nm of the dyes 1 to 12 produced specified in acetonitrile solution.

35

dye Absorption maximum
in nm 1 1026 . 2 970 3 1029 4th 1042 5 1026 6th 1032 7 · 1062 8th 1040 9 1028 10 1038 11th 1028 12th 1028

30 space of 0.5 hours with stirring and cooling 110 ml of acetic anhydride was added. When the exothermic reaction had ended, 18 g of cyclohexanone were added, whereupon the reaction mixture was warmed to room temperature and stirred for a further 2 hours. The precipitated pyrylium salt was filtered off and recrystallized from methanol. The yield was 16 g (25%). The melting point of the salt was 21O ⁰ C.

Analysis for C ₂ i H ₁₉ Cl O ₅ :

Calculated ... C 65.2, H 4.9, Cl 9.1;
found .... C 65.1, H 5.1, Cl 9.0.

B. Preparation of 2,4-diphenyl-5,6-cyclopentylpyrylium perchlorate

The salt was prepared as described under A using an equivalent amount of cyclopentanone instead of cyclohexanone. The salt was recrystallized from acetic acid. It had a melting point of 253-254 ° C.

Analysis for C ₂₀ H ₁₇ ClO ₆ :

Calculated ... C 64.5, H 4.6, Cl 9.4;
found .... C 64.7, H 4.5, Cl 9.2.

C. Preparation of 6-tert-butyl-2,4-diphenyl-.
S.oJ ^ -tetrahydrobenzoCbjpyrylium perchlorate

'50

Manufacture of intermediate products

The pyrylium salts required for the preparation of the pyrylium dyes used according to the invention can be produced by a process as described in »Helv. Chim. Acta. ", 44, pp. 1766 to 1783 (1961), is described. The preparation of some of these pyrylium salts will be described in more detail below.

A. Preparation of 2,4-diphenyl-5,6,7,8-tetrahydrobenzopyrylium perchlorate

A solution of 35 g of chalcone in 150 ml of ether was cooled in an ice bath, followed by stirring 70 g of 70% perchloric acid were added. The mixture was then added within a period of time Salt was prepared as described under A using an equivalent amount of 4-tert-butylcyclohexanone instead of cyclohexanone. The salt was recrystallized from ethanol. It had a melting point of 231 to 232 ° C.

Analysis for C ₂₅ H ₂₇ ClO ₅ :

Calculated ... C 68.0, H 6.2, Cl 8.0;
found .... C 67.9, H 6.4, Cl 7.8.

D. Preparation of 6-cyclohexyl-2,4-diphenyl-5,6,7,8-tetrahydrobenzo [b] pyrylium perchlorate

The salt was prepared as described under A using an equivalent amount of 4-cyclohexylcyclohexanone instead of cyclohexanone. The salt was recrystallized from acetic acid. It had a melting point of 216 to 218 ° C.

Analysis for C ₂₇ H ₂₉ ClO ₅ :

Calculated ..: C 69.1, H 6.2, Cl 7.6;
found .... C 68.9, H 6.3, Cl 7.6.

60

65

E. Preparation of 6-ethyl-2,4-diphenyl-5,6,7,8-tetrahydrobenzo [b] pyrylium perchlorate

The salt was prepared as described under A, using an equivalent amount of

4-ethylcyclohexanone instead of cyclohexanone. The salt was recrystallized from acetic acid. The melting point of the salt was 226 to 227 ° C.

Analysis for C ₂₃ H ₂₂ ClO ₅ :

Calculated ... C 66.8, H 5.3, Cl 8.5;
found .... C 66.7, H 5.6, Cl 8.5.

F. Preparation of 6-methyl-2,4-diphenyl-5,6,7,8-tetrahydrobenzo [b] pyrylium perchlorate

The salt was prepared as described under A using an equivalent amount of 4-methylcyclohexanone instead of cyclohexanone. The salt was recrystallized from acetic acid. The melting point of the salt was 207 bis 208 ° C. -

Analysis for C ₂₂ H ₂₀ ClO ₅ :

Calculated ... C 66.2, H 5.0, Cl 8.8;

found .... C 66.0, H 5.2, Cl 8.7.

G. Preparation of 2,4-bis (4-amyloxyphenyl) -5,6,7,8-tetrahydrobenzo [b] pyrylium perchlorate

The salt was prepared as described under A, using an equivalent amount of 4-amyloxy-4'-amyloxychalcone instead of chalcone. The obtained salt was recrystallized from acetic acid. It had a melting point of 99 to 100 ^° C.

Analysis for C ₃₁ H ₃₉ ClO ₇ ^{:! 3} °

Calculated ... C 66.6, H 7.0, Cl 6.3;
found .... C 66.4, H 7.0, Cl 6.4.

The dyes used in the invention excellent light and heat resistance arises from the fact that the dyes were not degraded even at 3tägjgem heating to a temperature of 15O ⁰ C. Likewise, no changes occurred when the dyes were exposed to room light for different lengths of time. In contrast, the known polymethine dyes, for example the known polymethine cyanine dyes, already decompose at room temperature and discolor on exposure.

The stability of the dyes used according to the invention in solution can, if desired, still be reduced

increase by a factor of 3 to 4 by adding an ultraviolet radiation absorbing compound. Such compounds are, for example, 2,4 - dihydroxybenzophenone, 2 - chloro - 4 - methoxy-4-hydroxyacetophenone and 2,4-dihydroxy-4'-methoxybenzophenone. This means that during manufacture of solutions of the dyes used according to the invention for the production of "Q-switches" the Solutions can advantageously be added to UV absorbers.

Because of their ability to absorb radiation of longer wavelengths of the spectrum, as well because of their excellent light and heat stability, those used according to the invention are suitable Dyes also act as infrared absorbing dyes in filter sheets in all cases where it is on a high absorption in the infrared range and a high transmission in the visible range of the spectrum arrives.

For the production of Q-switches, the dyes are in a known manner in a suitable solvent, such as chlorobenzene, dissolved and placed in the closed optical beam path within of the optical resonator of a laser. The invention is illustrated by the following example.

example

Solutions of the dyes 1 to 12 in chlorobenzene were prepared. The solutions contained 1 mg of dye per liter of solution. The solutions were then tested by placing them in the beam of a neodymium ion doped silica glass laser rod within the optical cavity. The dye solutions bridged a gap of 1 cm between the laser rod and the reflector. The laser rod was 7.62 cm long and 0.63 cm in diameter. Using this arrangement, a pulse of 50 x 10 ^-9 seconds obtained with a peak power of about 1 MW. The results obtained were found to be superior to the results obtained with other Q-switches, such as rotating mirrors or Kerr cells.

The use of the solvent was not found to be critical. Have proven to be particularly beneficial the dyes 1, 5 and 7 proved.

209547/3

Claims (2)

Patent claims: 1.Saturable absorbers in Q-switches in laser technology, characterized in that the following pyrylium dyes are used, which are built up from an anion of a strong acid and one of the following cations are: 8- [5- (6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetra- hydro-2,4-diphenyl-1-benzopyrylium 8 - [5 - (9,10 - dihydro-11H - benzo [a] xanthene-8 - yl) - 2,4 - pentadienylidene] - 8,9,10,11 - tetrahydrobenz p [a] xanthylium 8 - [6 - (4,6 - diphenyl - 2 H - pyran - 2 - ylidene) -2,4-hexadienylidene] -5,6,7,8-tetrahydro-2,4-di- phenyl-1-benzopyrylium "8 - [5 - (5,6 - dihydro - 2,4 - diphenylcyclo -" penta [b] pyran - 7 - yl) - 2,4 - pentadienylidene] -5,6,7,8 - tetrahydro - 2,4 - diphenyl -1 - benzopyrylium "8 - [5 - (6,7 - dihydro - 6 - methyl - 2,4 - diphenyl - ' 5 H-I -benzopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8 - tetrahydro - 6 - methyl - 2,4 - diphenyl-1-benzopyrylium "8- [5- (6-Cyclohexyl-6,7-dihydro-2,4-diphenyl-" 5H-l-benzopyran-8-yl) -2,4-pentadienylidene] -6-cyclohexyl-5,6,7,8-tetrahydro-2,4-diphenyl- _1 -benzopyrylium "8 - {5 - [2,4 - di - (4 - pentyloxyphenyl) - 6,7 - di -" hydro - 5 H - benzopyran - 8 - yl] - 2,4 - pentadienylidene} - 2,4 - di - (4 - pentyloxyphenyl) - 5,6,7,8-tetrahydro-1-benzopyrylium "8 - {5 - [2,4 - di - (4 - pentyloxyphenyl) - 6,7 - dihydro - 5 H -1 - benzopyran - 8 - yl] - 2,4 - pentadienylidene} - 5,6,7,8 - tetrahydro - 2,4 - diphenyl-1-benzopyrylium ~ 8- [5- (6-tert-butyl-6,7-dihydro-2,4-diphenyl- "5H-l-benzopyran-8-yl) -2,4-pentadienylidene] -6-tert.- butyl-5,6,7,8-tetrahydro-2,4-diphenyl-1-benzopyrylium "8- [5- (6-Cyclohexyl-6,7-dihydro-2,4-diphenyl-" 5 H-1 -benzopyran-8-yl) -2,4-pentadienylidene] -2,4 - di - (4 - pentyloxyphenyl) - 5,6,7,8 - tetra- _hydro-1-benzopyrylium ~ 8- [5- (6,7-dihydro-2,4-diphenyl-5 H-I -benzo- " thiopyran - 8 - yl) - 2,4 - pentadienylidene] -5,6,7,8 - tetrahydro - 2,4 - diphenyl -1 - benzo- _thiapyrylium 8- [5- (6,7-dihydro-2,4-diphenyl-5H-1-benzopyran-8-yl) -2,4-pentadienylidene] -5,6,7,8-tetrahydro-2,4- diphenyl-l -benzothiapyrylium 2. Saturable absorber according to claim l, characterized in that the anion is a perchlorate anion is.