JPS6396639A - Organic nonlinear type optical compound - Google Patents

Abstract

PURPOSE:To obtain the titled compd. which has large optical nonlinearity and high threshold value for laser breakdown and permits crystallization, thin film formation, etc., by using the compd. expressed by the specific formula as a material to be used for optical information processing, optical communication, etc. CONSTITUTION:Substd. furfuryl aldehyde and substd. aniline are mixed in alcohol or benzene in the presence of a Lewis acid as a catalyst and the mixture is slightly heated at need and is condensed to obtain the compd. expressed by the formula. The doner type substituent expressed by the formula includes an amino group such as monomethylamino, alkyl group such as methyl, hydroxy group such as hydroxymethyl, alkoxy group such as methoxy, etc., which are better as the doner property is weaker. The resultant compd. includes N-[2-(5- nitrofurfurylidene)]-4-dimethylaminobenzenamine, N-[2-(5-nitrofurfurylidene)]-4- methoxybenzenamine, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an organic nonlinear optical material used in optical information processing, optical communication, etc.

[Prior Art] Many materials exploration studies have been conducted with the aim of realizing nonlinear optical elements as new elements in the field of optoelectronics. It is attracting attention because of its high-speed response.

In particular, regarding second-order optical nonlinearity, a series of reports centered on benzene derivatives (AC3S'/J) O5iLIm 5
eries 233 (1983)), in order to break the central symmetry of the crystal, which is a problem in developing optical nonlinearity in the crystal state, optically active substituents and substituents with a large ability to form hydrogen bonds are added to π. The idea of introducing it into an electronically conjugated system has been taken during molecular design, and there are some success stories.

On the other hand, third-order optical nonlinearity has been reported for several types of polydiacetylene compounds, which have a greater effect than inorganic crystals and can be made into single crystals or thin films by solid phase polymerization.

[Problems to be solved by the invention] However, the success story with benzene derivatives is that it is difficult to create a bulk state with sufficiently large optical nonlinearity to withstand practical use, such as molecular crystals. The drawback is that the hyperpolarizability, which is an important factor in

In addition, as mentioned above, polydiacetylene has greater optical nonlinearity than inorganic crystals, but since the compound absorption due to the long π-electron conjugated system reaches into the visible long wavelength region, This leads to a decrease in the laser destruction threshold, which has the disadvantage of being impractical.

An object of the present invention is to provide a practical organic nonlinear optical compound that has large optical nonlinearity and a high laser destruction threshold, and can be roughly crystallized and formed into a thin film.

Means for Solving Problem F] In order to achieve the above object, the present invention has the following structure.

That is, the present invention provides the following general formula ri: donor substituent R1-R6: hydrogen or any substituent This invention relates to an organic nonlinear optical compound represented by

The optical nonlinearity, or hyperpolarizability, of a compound can be said to be an index for estimating the fluctuation of π electrons in response to the optical electric field. However, in the case of low molecular weight organic compounds, this fluctuation depends on the length of the π electron conjugated system and the ground state. It can be said that the value increases with the strength of the interaction between the excited state and the excited state. Therefore, in the present invention, the π-electron conjugated system of the benzene ring is lengthened via the furan ring and the amine bond for connection thereto, and donor and acceptor substituents are introduced to increase the hyperpolarizability. .

Introducing a donor substituent at the 4-position of the benzene ring is effective because it increases the resonance effect due to charge transfer interaction and increases the optical nonlinearity of the compound.

The compound of the present invention can be produced by mixing a substituted furfurylaldehyde and a substituted aniline in alcohol or benzene in the presence of a Lewis acid as a catalyst, and if necessary heating the mixture slightly to condense the compound. Obtained by synthetic methods. (()1.H, sprung, Chem, R
ev 26297 (1940)) Examples of donor substituents in the present invention include amine, monomethylamino,
Amino groups such as dimethylamino, diethyl, amine, ■-butylamino, t-butylamino, L-[(2-hydroxymethyl)-pyrrolidinyl], L-alaninyl, L
-Serinyl, L-tyrosinyl, and other various amino groups having optical activity are listed first.

Examples of compounds include N-[2-(5-nitrofurfurylidene)]-]4-dimethylaminobenzenamine N-[
2-(5-nitrofurfurylidene)]-]3-dimethylaminobenzenamine N-[2-(5-nitrofurfurylidene)]-]4-monomethylaminobenzenamine N-[
2-(5-nitrofurfurylidene)]-]2-monomethylaminobenzenamine N-[2-(5-nitrofurfurylidene)]-4-(L)-alaninylbenzenamine,
N-[2-(5-nitrofurfurylidene)]-4-(L
)-[(2-hydroxymethyl)-pyrrolidul]penzenamine, N-[2-(5-nitrofurfurylidene)]
-4-(L)-serinylbenzenamine and the like.

Furthermore, in order to suppress the absorption of the compound to the relatively short wavelength side and to suppress the decrease in the laser destruction threshold due to absorption, it is effective to weaken the donor property of the substituent. A weak donor substituent is defined by the Llammott substituent constant σ, 0〉
σ > -0,4 and halogen p p , for example, alkyl groups such as methyl, ethyl, n-butyl, t-butyl, hydroxyalkyl groups such as hydroxymethyl, hydroxyethyl, hydroxy groups, and methoxy, ethoxy, Examples include alkoxy groups such as t-butoxy. At this time, the optical nonlinearity of the compound is
Although it is generally weaker than when a strong donor substituent such as an amino group is introduced, the use of a methoxy group, a hydroxy group, etc. is particularly effective because it does not significantly reduce optical nonlinearity.

Examples of compounds include N-[2-(5-nitrofurfurylidene)]-]4-methoxybenzenamine N-[2-(
5-nitrofurfurylidene)]-4=hydroxybenzenamine, N-[2-<5-nitrofurfurylidene)]-
]4-ethylbenzenamine N-[2-(5-nitrofurfurylidene)]-]4-methylbenzenamine N-[
2-(5-nitrofurfurylidene)]-]4-ethylbenzenamine N-[2-(5-nitrofurfurylidene)]
-]4-hydroxymethylbenzenamine N-[2-(5
-Nityrofurfurylidene>]-]4-Chlorbenzenamine N-[2-<5-Nitrofurfurylidene/)]-]4
-promobenzenamine N-[2-(5-nitrofurfurylidene)]-]4-iodobenzenamine and the like.

Furthermore, in the -IR formula, there are no particular restrictions on the introduction of substituents other than nitro groups and donor groups; however, when introducing substituents, it is important that they do not have a large effect on the π-electron conjugated system of the parent skeleton. is necessary. Preferably, the substituent has a Hammett's substituent constant σ of about 1σ I × p 0.4. Further, more preferred substituents include hydrogen bond-forming hydroxyalkyl groups such as hydroxymethyl and hydroxyethyl, and acetamino groups.

Examples of compounds include N-[2-(5-nitrofurfurylidene)]-]4-monomethylamino-3-acetaminobenzenamine N-[2-(5-nitrofurfurylidene)]-]4 -dimethylamino-3-hydroxymethylbenzenamine N-[2-(5-nitrofurfurylidene)
]-]4-methoxy 2-acetaminobenzenamine N
-[2-(5-nitrofurfurylidene)]-]4-methoxy3-acetaminobenzenamine N-[2-(5-
nitrofurfurylidene)]-]4-hydroxy-2-methylbenzenamine N-[2-(5-nitrofurfurylidene>]-]4-methyl-3-hydroxyedylbenzenamine N-[2-(5-di trofurfurylidene)]-]4
-bromo 2-methylbenzenamine N-[2-(5-nitrofurfurylidene)]-]4-hydroxymethyl-2
- Examples include thalolbenzenami.

Note that deuteration of a compound has a near-infrared absorption shift effect, but has the same nonlinear optical effect as a non-deuterated compound. Therefore, in the nonlinear optical compound, some or all of the hydrogens may be replaced with deuterium.

[Example] Synthesis of N-[2-<5-nitrofurfurylidene>]-]4-methoxybenzenami and optical nonlinearity 2.82 CI (20+r+mol ) of 5-nitrofurfural and 2.46 g (20 mmol) of p-
Anisidine was added, about 60 ml of ethanol was used as a reaction solvent, and the mixture was stirred at room temperature for about 10 minutes.

Next, about 17 mg (1 mmol) (7) p-) Rue:
/sl'v acid was added as a catalyst and stirring continued at room temperature for about 3 hours. At this time, the yellow-brown target product produced by the condensation reaction began to crystallize.

After confirming the completion of the reaction using thin layer chromatography using chloroform as a developing solvent, stirring was stopped.

The precipitated crude crystals were collected and washed with cold ethanol.

When the yellowish brown recrystallization obtained here was recrystallized with a mixed solvent of chloroform/ethanol (1/2), yellow needle-shaped crystals were obtained, and 24 crystals were collected and dried under vacuum.

4.25 g (yield: 86.4%) of the target product was obtained. Identification was performed by IR and elemental analysis.

In addition, this compound was recrystallized by evaporation from a chloroform solution, and was crystallized into a highly transparent square shape (3 mm x 5 m).
It was possible to grow a crystal of 2mm x 2mm).

Melting point>123.0~124.0℃ 1620cm' (-CH=N-) 1350cm' (-NO2) For details, see the drawing Elemental analysis> Examine the optical nonlinearity of the sample obtained by the above synthesis method For the second. The third harmonic is determined by the powder method (s, k.

Kurtz, T., T., Perry, J., Ap.
pl, Phys 393798 (1986)). The light source used for the measurement was a Nd:YAG laser, and the sample was ground to 10 μm or less in a mortar.

The measurement results are shown in Table 1. N-[2-(5-
Nitrofurylidene)]-]4-methoxyanily has a tertiary effect that is 16 times that of a typical polydiacetylene, 2,4-hexadiyne-1,6-thiol bis(p-toluenesulfonate) polymer (PTS). It showed excellent properties.

Table 1. Organic nonlinear optical compounds SHG, THG (λ: 1
．． 06μm) Note) Initial value before deterioration ``Effect of the invention'' According to the present invention, by introducing a nitro group at the 5-position of furfurylidene in N-(2-furfurylidene>penzenamine) and a donor substituent to penzenamine. , a practical nonlinear optical compound with large optical nonlinearity and high destruction threshold is obtained.

[Brief explanation of the drawing]

The drawing shows a chart of infrared absorption spectra of compounds of examples of the present invention.

Claims (5)

[Claims] (1) The following general formula ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ D: Donor substituent R1 to R6: hydrogen or any substituent An organic nonlinear optical compound represented by (2) The organic nonlinear optical compound according to claim (1), which has a donor substituent at the p-position. (3) The organic nonlinear optical compound according to claim (1) or (2), wherein the donor substituent has weak donor properties. (4) The organic nonlinear optical compound according to claim (2), wherein the donor substituent is a methoxy group or a hydroxy group. (5) The organic nonlinear optical compound according to claim (1), wherein some or all of the hydrogens in the compound are deuterated.