JPH0613521B2 - Nitrogen-containing heterocyclic compound and its crystal - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel substance, particularly an organic nonlinear optical compound used in optical information processing, optical communication and the like, and a crystal thereof.

[Prior Art] As a new element in the field of optoelectronics, many researches have been conducted on material search aiming at the realization of nonlinear optical elements. In recent years, organic compounds having a π-electron conjugated system have been found to have high performance and It is attracting attention because of its high-speed photoresponsiveness.

In particular, materials having second-order optical non-linearity have been studied in various compound systems, and there are many reviews. (1) ACS symposium series 233 (1983), 2) D.
J. Williams Angew.Chem.Int.Ed.Engl.23 p690 (1984). ) The optical nonlinearity of an organic compound having a π-electron conjugated system is said to be due to the fluctuation of π-electrons upon the incidence of laser light.To increase this fluctuation, the π-electron conjugated system has a donor property and an acceptor property. The conventional molecular design guideline was to introduce the above substituents.

Therefore, the compound according to the above molecular design guideline, that is,
A compound in which a donor group or an acceptor group is introduced into a π-electron conjugated system has a strong dipole-dipole interaction between molecules, and has a centrosymmetric crystal structure in which dipoles of two molecules cancel each other. Easy to form.

However, such a centrosymmetric crystal does not exhibit the second-order optical nonlinearity.

In previous research, in order to break the central symmetry of the crystal, which is a problem in expressing optical nonlinearity in the crystalline state, an optically active substituent or a substituent having a large hydrogen bond forming ability was introduced into the π-electron conjugated system. The idea to do is made at the time of molecular design,
There is an example in which a relatively large optical nonlinearity is exhibited.

N, N-Dimethyl-2-acetylamino-4-nitroaniline (DAN), N- (4-nitrophenyl)-
A benzene derivative such as (L) -prolinol (NPP) is a typical example.

[Problems to be Solved by the Invention] However, these do not sufficiently have various characteristics (optical nonlinearity, crystallinity, storage stability, etc.) necessary for practical application of the nonlinear optical element.

Therefore, the development of new compounds is expected, and the material search is actively conducted.

An object of the present invention is to provide a novel organic non-linear optical compound capable of producing a molecular crystal having a small dipole moment and a large optical non-linearity, and a crystal thereof.

[Means for Solving Problems] In order to achieve the above object, the present invention has the following configurations.

"A nitrogen-containing heterocyclic compound, which is an organic compound represented by the following general formula [1].

E ¹ , E ² : A crystal comprising an acceptor substituent and a compound of the formula [1].

As described above, it can be said that the central symmetry of the crystal is largely due to the dipole-dipole interaction between the molecules. Therefore, in order to break the central symmetry of the crystal, it is very effective to carry out molecular modification on the compound system having a basic structure in which the dipole moment of the molecule is reduced.

In the following compound system [2], a lone electron pair of a hetero atom can serve as a donor site for adjacent benzene rings at both ends.

In the present invention, an acceptor substituent is introduced into an aromatic ring or a heteroaromatic ring at both ends of the following compound system [2] in which a bond connecting two benzene rings also has a donor property,
It was found that a large optical non-linearity can be expressed by making the structure containing two optical non-linearities in one molecule by the charge transfer interaction between the donor and the acceptor.

In this case, the compound has a symmetric or pseudo-symmetric structure,
Since it is possible to suppress an increase in dipole moment due to the absorption having a longer wavelength and the introduction of the acceptor substituent, it is effective in the following point.

A) It is possible to suppress deterioration of optical nonlinearity and deterioration of compounds due to absorption of higher harmonics.

B) Since the dipole moment is small, packing control for the bulk state formed by molecules, that is, molecular orientation becomes easy.

That is, the compound of the present invention easily loses the central symmetry in the bulk state, for example, the crystalline state due to the intermolecular cohesive force such as hydrogen bond, and exhibits the optical nonlinearity. When a hydrogen-bonding or sterically hindering substituent is introduced into the aromatic ring or heteroaromatic ring, optical non-linearity is particularly likely to be exhibited.

When an acceptor substituent is introduced into a site having a large resonance effect, the charge transfer interaction can be strengthened and the optical nonlinearity of the compound can be increased, which is effective.

The site having a large resonance effect here is the p-position of amino (-NH-) in the above formula [2], that is, the 3- and 9-positions of the benzoxazinobenzoxazine mother skeleton.

Furthermore, the acceptor substituents E ¹ and E ^{2 of} the formula [1]
Are the same, the structure of the compound becomes symmetric, and the above advantages A) and B) are more remarkable and effective.

The compound of the present invention is a general method for synthesizing an imine compound in which glyoxal and a 2-aminophenol derivative substituted with an acceptor group are mixed and condensed in alcohol or benzene in the presence of a Lewis acid as a catalyst ((( MM
Sprung, Chem. Rev 26 297 (1940)).

Examples of the acceptor substituent in the present invention include nitro, cyano, isocyanate, aldehyde, alkyl carboxylate such as methyl carboxylate and ethyl carboxylate, sulfonyl, halogen and the like.

It is particularly preferable to introduce a nitro group as the acceptor substituent in order to improve the optical nonlinearity of the compound.

The introduction of a substituent to a position other than the position where the acceptor substituent is introduced on both ends of the benzene ring is not particularly limited, but when it is introduced, it must be a substituent that does not significantly affect the π-electron conjugated system of the mother skeleton. is important.

For example, Hammett's substituent constant σ is −0.4 <σ
It is a substituent of about 0.4. Preferred are a hydrogen-bonding hydroxyl group, an alkoxy group such as methoxy and ethoxy, an alkanoylamino group such as acetylamino and ethylcarbonylamino, and a carbamoylamino group.

Deuteration of a compound has a near-infrared absorption shift effect and the like, but has the same non-linear optical effect as a compound not deuterated. Therefore, in the above nonlinear optical compound, some or all of the hydrogen may be deuterium-substituted.

[Example] Example 1 Synthesis and optical nonlinearity 200 ml equipped with reflux condenser and magnetic stirrer
6.16 g (40 mmol of 2-amino-5-nitrophenol and about 17 mg (1 mmol) of p-toluenesulfonic acid) were placed in the three-necked flask described above, and about 100 ml of ethanol was used as a reaction solvent, and at about 50 ° C. for 10 minutes. It was stirred.

Next, 2.90 g (20 mmol) of glyoxal aqueous solution (40 wt%) was gradually added dropwise to the yellowish brown reaction solution.

Then, the reaction temperature was kept at 50 ° C., and the stirring was continued for about 3 hours, whereby the yellow target product began to crystallize.

After confirming the completion of the reaction by thin layer chromatography using chloroform as a developing solvent, stirring was stopped. The precipitated crude crystals were collected and washed with cold ethanol.

The yellow crude crystals obtained here were mixed with acetone / chloroform (3
When recrystallized with the mixed solvent of (1/1), yellow on-plate crystals were obtained, which were collected and vacuum dried.

(Target product 3.88 g (yield 58.7%)) Identification was performed by IR, NMR and elemental analysis (Table 1
And FIG. 1 and FIG. 2).

In addition to the above NMR results, it was further confirmed by single crystal structure analysis that the compound of this example had a benzoxazino benzoxazine mother skeleton generated by the ring closure reaction of diimine.

In the single crystal structure analysis, a yellow flat plate crystal obtained by the above recrystallization was used as a single crystal sample.

The measurement was carried out with a MoKα ray (λ = 1.71069Å) using a Rigaku AFC6R diffractometer.

The results are shown in Tables 2 and 3 and FIG. It has been shown that the compound of this example has a molecular structure having benzoxazinobenzoxazine as a mother skeleton.

Next, in order to investigate the optical non-linearity of this compound, the second harmonic wave method (SK Kurtz, TTPerry, J. Appl. Phys 39 3798 (1
966)). The light source used for the measurement is Nd: Y
The sample was crushed with an AG laser to a size of 10 μm or less using a mortar.

The measurement results are shown in Table 5. The compound according to the present invention showed a large optical non-linearity of 40 times that of the standard known compound, urea.

Example 2 Synthesis and optical nonlinearity 200 ml equipped with reflux condenser and magnetic stirrer
6.69 g (40 mmol) of methyl-
4-amino-3-hydroxybenzoate and about 17 mg (1
(mmol) p-toluenesulfonic acid is added, and about 100 ml
Was used as a reaction solvent, and the mixture was stirred at about 50 ° C. for 10 minutes.

Next, 2.90 g (20 mmol) of glyoxal aqueous solution (40 wt%) was gradually added dropwise to the blackish brown reaction solution.

After that, the reaction temperature was kept at 50 ° C. and stirring was continued for about 3 hours, and then the light brown target product began to crystallize.

After confirming the completion of the reaction by thin layer chromatography using chloroform as a developing solvent, stirring was stopped. The precipitated crude crystals were collected by filtration and washed with cold ethanol.

The light brown crude crystals obtained here were recrystallized from methyl ethyl ketone to give colorless needle crystals, which were collected by filtration and vacuum dried.

(3.54 g of the desired product (yield 49.7%), decomposition temperature> 266 ° C.) Identification was carried out by IR, NMR and elemental analysis (see FIGS. 4, 5 and Table 4).

Next, in order to investigate the optical nonlinearity of this compound, the second harmonic wave was measured by the powder method (SKKurtz, TTPerry, J.Appl.Phys 39 3798).
(1966)). The light source used for the measurement is Nd:
With a YAG laser, a sample crushed to 10 μm or less by a mortar was used.

The measurement results are shown in Table 5. The compound according to the present invention showed a large optical non-linearity of 10 times that of the standard known compound, urea.

Further, single crystal structure analysis of colorless needle-like crystals obtained by the method of Example 2 was performed.

The results are shown in Tables 6 and 7 and FIG. The crystals obtained in Example 2 showed that the compound molecule having benzoxazino benzoxazine as a mother skeleton had a non-centrosymmetric structure and belonged to an orthorhombic crystal.

[Effects of the Invention] According to the present invention, a novel nitrogen-containing heterocyclic compound can be obtained. This substance has a particularly excellent effect as a nonlinear optical crystal.

[Brief description of drawings]

FIG. 1 shows an IR chart of the compounds of the examples of the present invention. FIG. 2 shows an NMR chart of the compounds of the examples of the present invention. FIG. 3 shows the molecular structure obtained by single crystal structure analysis of the compound of Example 1 of the present invention. FIG. 4 shows an IR chart of the compound of Example 2 of the present invention. FIG. 5 shows an NMR chart of the compound of Example 2 of the present invention. FIG. 6 shows the molecular structure obtained by single crystal structure analysis of the compound of Example 2 of the present invention.

Claims (10)

[Claims] 1. A nitrogen-containing heterocyclic compound, which is an organic compound represented by the following general formula [1]. E ¹ , E ² : an acceptor substituent 2. The organic compound according to claim (1), wherein E ¹ and E ² of the formula [1] are substituted at a site having a large resonance effect. 3. The organic compound according to claim ¹ , wherein E ¹ and E ² of the formula [1] are the same substituents. 4. The organic compound according to claim (1), wherein E ¹ and E ² of the formula [1] are nitro groups. 5. An organic compound represented by the formula [1] is represented by the following formula: 3,9-dinitro-5a, 6,11a, 12-tetrahydro [1, represented by
The organic compound according to claim (1), which is 4] benzoxazino [3,2-b] [1,4] benzoxazine. 6. An organic compound represented by the formula [1] is represented by the following formula: Claims characterized in that it is 3,9-dimethoxycarbonyl-5a, 6,11a, 12-tetrahydro [1,4] benzoxazino [3,2-b] [1,4] benzoxazine represented by First
The organic compound according to item (1). 7. A compound of the formula [1], wherein a part or all of the hydrogen is deuterated.
The organic compound according to item (1). 8. A crystal comprising an organic compound represented by the following general formula [1], having a non-centrosymmetric structure and having a non-linear optical effect. 9. An organic compound represented by the general formula [1] is represented by the following formula: 3,9-dinitro-5a, 6,11a, 12-tetrahydro [1, represented by
The crystal according to claim (8), which is 4] benzoxazino [3,2-b] [1,4] benzoxazine. 10. An organic compound represented by the general formula [1] is represented by the following formula: Claims characterized in that it is 3,9-dimethoxycarbonyl-5a, 6,11a, 12-tetrahydro [1,4] benzoxazino [3,2-b] [1,4] benzoxazine represented by First
The crystal according to item (8).