JPH02226125A - Organic nonlinear optical materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to organic nonlinear optical materials. More specifically, it is useful in fields such as wavelength conversion of laser light, optical communication, optical integrated circuits, and optical information processing.

We use organic nonlinear optical materials that can be used in a wide range of visible light.

Conventional technology As a new element in the field of optoelectronics.

Many efforts have been made to search for materials with the aim of realizing nonlinear optical elements. Nonlinear optical materials are broadly classified into inorganic materials and organic materials. Conventionally, nonlinear optical materials include EVA, KH2
Inorganic dielectrics such as PO4 and L1Nbo3 are used.

However, these inorganic nonlinear optical materials do not have sufficient optical nonlinearity and require the production of extremely large single crystals for industrial use. In addition, strong laser light is required to produce a sufficient nonlinear optical effect.

On the other hand, organic compounds with a π-electron conjugated system are attracting attention as nonlinear optical materials due to the high performance and high-speed response of the molecules themselves (M-inear Optic).
al Properties of Organ
ic and PolymericMateria
ls, ACS Sympasrum 5eri
es 233 (1983)).

In order to generate second harmonics due to second-order nonlinear optical effects, it is necessary to remove the center of symmetry of the crystal. The methods include introduction of substituents into asymmetric positions, use of optically active compounds, use of clathrate compounds, use of counter ion selection in monomolecular salts, use of hydrogen bonds between five molecules, control of dipole moment, LB Examples include the use of membranes.

For example, m-nitroaniline and 2-methyl-4-
Nitroaniline (hereinafter abbreviated as MNA) is known, and US Patent No. 4.199. OH issue, JP-A-55-500
．． There are publications such as Publication No. 980.

Although these organic compounds have excellent optical nonlinearity, they are still not sufficient, and they also have absorption in the visible light region, particularly in the vicinity of 400 nys.

When applying organic nonlinear optical materials to wavelength conversion, particularly to second harmonic generation, there is a need for materials that do not absorb light at the wavelength of the second harmonic. For example, when applied to second harmonic generation of a GaAlAs semiconductor laser operating in the near-infrared wavelength region, a material that does not have absorption near 400 nm is desired. Also.

When used in combination with a shorter wavelength light source,
Transparency in a corresponding wavelength range is required.

On the other hand, as a fluorine compound with a π-electron conjugated system, 1.3
-Dioxolane derivatives are known (Seibu, Kono, Proceedings of the 13th Fluorine Chemistry Symposium, p9B (1988))
.

Problems to be Solved by the Invention Accordingly, an object of the present invention is to provide an organic nonlinear optical material that exhibits optical nonlinearity in a crystalline state and can be used in the short wavelength region of visible light.

Means for Solving the Problems In order to achieve the above object, the present invention is characterized by having a trifluoromethyl group that does not absorb light in the visible light region as an acceptor substituent. That is, the following formula [E]: Compound example (wherein R1 and R2 are each an optionally substituted aliphatic hydrocarbon group or an optionally substituted aromatic hydrocarbon group, and R7 and This is an organic nonlinear optical material consisting of a 1,3-dioquinrane derivative represented by R2, which can be combined to form a cyclic structure.

Examples of the substituent represented by R, R2 include aliphatic hydrocarbon groups such as methyl group, ethyl group, n-propyl group, and i-propyl group, and aromatic hydrocarbon groups such as phenyl group and naphthyl group. can be mentioned.

Further, hydrogen of these hydrocarbon groups may be substituted with any substituent.

Further, R1 and R2 may be combined to form a cyclic structure, such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and the like.

Specific examples of compounds in the present invention are shown below.

Compounds of the present invention under room temperature conditions? -bromo 3゜3,3
- Can be obtained by the reaction of trifluoropropene and ketones (Seibe, Kono, Proceedings of the 13th Fluorine Chemistry Symposium, p. 9B (1988)) - As mentioned above, p
-Nitroaniline compounds such as nitroaniline, MNA, and m-nitroaniline exhibit large optical nonlinearity at the single molecule level, while also having light absorption in the visible region.

This is because the light absorption by the nitro group is near the visible region, and furthermore, the light absorption band is shifted to longer wavelengths due to the bathochromic effect due to the donor-acceptor effect.

In other words, one way to obtain a compound that does not absorb light in the visible region is to select a group other than the chromophore nitro group as the acceptor substituent. Has strong acceptor properties,
This is achieved by selecting a trifluoroalkyl group that has no absorption in the visible region.

The compound of the present invention is composed of a trifluoromethyl group with strong acceptor properties and a ketal structure with donor properties sandwiching a double bond which is a π-conjugated system. Such a molecular structure is effective because it can increase charge transfer interaction and therefore increase optical nonlinearity.

Example Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 [Synthesis of 2,2,5,5,-tetramethyl-4-trifluoroethylidene-1,3-dioxolane (Compound Example 1 whose structure was shown above)] A reflux condenser was placed in a 300-three-necked flask, Attach a dropping funnel and stirrer and add dry tetrahydrofuran (T
HF)120- was introduced, and the internal atmosphere was replaced with nitrogen.

Here, 20g of sodium methoxide powder (370,
4 gaol) was carefully added and stirred.

Next, 32.4 g (1
85,1 mmol) and acetone 22 g (378,8 m
A mixture of 1 Iol) was added dropwise over 2 hours. At this time, the temperature was maintained at 20° C. by vigorous stirring. After the completion of 0 dropwise addition, the temperature was maintained at 20° C. and further stirred for 2 hours.

Next, 100% of water was added dropwise to the reaction mixture at 0° C., followed by extraction with 240% of diethyl ether.

The organic layer was washed with saturated brine until the aqueous layer became neutral, and then dried over magnesium sulfate.

After carefully distilling off the solvent under reduced pressure, the extract was purified by column chromatography using hexane and silica gel to obtain colorless crystals. The yield was 36 g (171.4 x 1), the yield was 92.4%, and the melting point was 84°C.

The analysis results of various spectra are shown below.The measurements are 'H-NMR and '9F-NMR, respectively.
Arian VXR-300A, 13C-NMR is JO
EL made FX-100, IR is Jasca made s+odel
It was carried out using A-200.

'H-NMR: δ (CDC13) PPPI348
(s, 6H) 1.53 (s, 6H) 4.48 (q, I H,j =7.2 Hz)”F
-NMR: δ (CDC13)PP■-57,14
(d) I3C-NMR: δ (CDC13) PPlI
27.9B, 29.47, 82.92.83, 7
9. 114.3B, 124.23, 1813. [1
2I R: (KB r)c@-' 3000, 1680, 1390, 1270, 1185,
1120.1020.945 This compound can be easily crystallized using a solvent such as an alcohol-water mixed solvent.

Next, the powder method proposed by Kurtz et al.
tz.

T., T., Perry, J., Appl., Phys.
, 3% 3713B (19H)) to examine the presence or absence of optical nonlinearity. The sample is a crystal obtained by the above method with an average particle size too p,
The second harmonic (wavelength 532n) generated by irradiation with the fundamental wave (wavelength 1084n) of Nd:YAG laser was observed.

As a result, second harmonic green light was observed, and
By dissolving the compound in ethanol, a solution of 10-4 o1/fL was obtained, and its visible light transmission characteristics were investigated by measuring the absorption spectrum with an ultraviolet/visible spectrophotometer.厘、λcut-of
f was 247 nm. Here, input sag is the maximum wavelength of light absorption on the longest wavelength side, and λcut
-off (cutoff wavelength) is the absorption edge on the short wavelength side.

Example 2 [Synthesis of 2,5,-dipentamethylene-4-trifluoroethylidene-1,3-dioxolane (Compound Example 2 whose structure was shown above)] A 300 J three-way flask was equipped with a reflux condenser, a dropping funnel,
Attach a stirrer and dry tetrahydrofuran (
THF) 120- was added, and the internal atmosphere was replaced with nitrogen. Here, add 20g of sodium methoxide powder (370
, 4■ Peng o1) was carefully added and stirred.

Next, 32.4 g (1
85,1 intestinal layer of) and 37 g of cyclohexanone (37
7.0 OL of the mixture was added dropwise over 2 hours. At this time, the temperature was maintained at 20° C. by vigorous stirring. After the completion of 0 dropwise addition, the temperature was maintained at 20° C. and further stirred for 2 hours.

Next, 100 μl of water was added dropwise to the reaction mixture at 0° C., followed by extraction with 240 μl of diethyl ether.

The organic layer was washed with saturated brine until the aqueous layer became neutral, and dried over magnesium sulfate.

After carefully distilling off the solvent under reduced pressure, the extract was purified by column chromatography using hexane and silica gel to obtain colorless crystals. Yield 52.8g (181,
2m*ol), yield 87.9%, and melting point 64°C. The analysis results of various spectra are shown below.

'H-NMR: δ (CDC13) PP■1.17~1
．． 85 (m, 20H) 4.43 (q, IH) 19 F-NMR: δ (CDC13) PP intestine-513,95 (d) I R: (neat) cm-”2350.
1835.1385.1255.1230.1115.
1080,860 This compound can also be crystallized according to Example 1, and when the presence or absence of optical nonlinearity of the crystal was examined using the method of Example 1, green light of the second harmonic was confirmed. It was done.

Also, when the visible light transmission characteristics were similarly investigated according to Example 1, λ was a! is 208n+w, λcut-off is 2
It was 44 us.

As is clear from these results, the compound of the present invention is more transparent in a wide range from visible light to ultraviolet light region than conventional compounds, and exhibits optical nonlinearity.

Effect of the invention As stated above, according to the compound of the present invention.

Utilizing the fact that it is more transparent than conventional materials from visible light to ultraviolet light, it can be used in combination with short wavelength light sources in the fields of wavelength conversion and various information processing.

Claims (1)

[Claims] Formula [I]: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] (In the formula, R_1 and R_2 are each an optionally substituted aliphatic hydrocarbon group or an unsubstituted aliphatic hydrocarbon group. (R_1 and R_2 may be combined to form a cyclic structure.