JP2005263738A - Two-photon-absorbing material comprising porphyrin oligomer derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-photon-absorbing material having sufficient two-photon-absorbing properties. <P>SOLUTION: The two-photon-absorbing material consists mainly of a compound of the formula(1)(wherein, Ar is an aromatic ring-bearing substituent; M is a transition metal ion; wherein the substituents Ar may be different from each other) or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a two-photon absorption material mainly composed of a porphyrin oligomer derivative having a large two-photon absorption cross section.

  Recently, among the nonlinear optical characteristics of organic compounds, compounds having two-photon absorption characteristics have attracted a great deal of attention from the viewpoint of application to optical memory, two-photon imaging of biological tissues, and two-photon photodynamic therapy (PDT).

  As a compound having such a large two-photon absorption cross section, a compound according to the following formula (3), a porphyrin derivative described in Non-Patent Document 1, and the like are known.

J. et al. Am. Chem. Soc. 2003, 125, 13356

  However, the two-photon absorption cross section of the compound represented by the above formula (3) is about several tens of GM. Moreover, the two-photon absorption cross-section of the porphyrin derivative described in Non-Patent Document 1 is 2000 GM or less. For this reason, these compounds are insufficient in terms of the two-photon absorption amount for application to a two-photon absorption material, and development of a compound having an even larger two-photon absorption cross section of about several thousand to several tens of thousands GM. Is desired.

  Accordingly, an object of the present invention is to provide a two-photon absorption material having sufficient two-photon absorption characteristics.

（上記式（１）及び（２）中、Ａｒは、芳香環を有する置換基を示す。また、上記Ｍは、遷移金属イオンを示す。さらに、それぞれのＡｒは異なってもよい。） This invention solved the said subject by using the 2-photon absorption material which has as a main component the compound concerning following formula (1) or (2).

(In the above formulas (1) and (2), Ar represents a substituent having an aromatic ring. Further, M represents a transition metal ion. Furthermore, each Ar may be different.)

  Since a specific porphyrin oligomer derivative is used, a large two-photon absorption cross section can be obtained, and it can be used as a two-photon absorption material.

Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.
The two-photon absorption material according to the present invention contains a porphyrin oligomer derivative as a main component. As an example of this porphyrin oligomer derivative, the amount of porphyrin represented by the compound according to the following formula (1) (hereinafter referred to as “compound (1)”. The same applies to compounds of other numbers). And porphyrin trimers represented by the following compound (2).

  In the above formulas (1) and (2), Ar represents a substituent having an aromatic ring. M represents a transition metal ion.

Examples of the aromatic ring that Ar has include a benzene ring, a naphthalene ring, and an anthracene ring. Moreover, this aromatic ring may further have a substituent. Such a substituent may have any number of substituents as long as it does not significantly impair the aromaticity of the aromatic ring of Ar. The organic group having 1 to 20 carbon atoms is preferable from the viewpoint of improving the two-photon absorption cross-sectional area due to various effects. Specifically, for example, an alkyl group, an alkoxy group, a phenyl group, a naphthyl group, a phenanthryl group, an anthryl group, etc. Aryl groups and the like.
In addition, each Ar in said formula (1) and (2) may be the same, or may differ.

  Examples of the transition metal include ions of copper, silver, nickel, cobalt, zinc, cadmium and the like. Among these, a divalent metal ion or a metal ion having a planar coordination is preferable in terms of structural stabilization by coordination, chemical stabilization, and tuning of absorption wavelength.

  Examples of the compound (1) include the following compound (4) and compound (5).

  Moreover, the following compound (6) is mention | raise | lifted as an example of the said compound (2).

  Since said compound (1) and compound (2) have a large two-photon absorption cross section, they can be used as a main component of a two-photon absorption material. The evaluation of the two-photon absorption cross-section can be performed by the method described in [Evaluation of two-photon absorption cross-section] in Examples described later, and the above compounds (1) and (2) Compared with the two-photon absorption dyes reported so far, the two-photon absorption cross-section is several orders of magnitude larger, preferably a two-photon absorption cross-section of 9000 GM or more.

  The two-photon absorption material according to the present invention can be used for various applications such as an optical memory recording medium.

Next, the present invention will be described more specifically using examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
[Synthesis of Compound (4)]
(Production of Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-bromoporphyrin)
CHCl ₃ (100 mL) to 5, 15-di (3,5-t-butylphenyl) -porphyrin (synthesized according to the method described in JS Manka and DS Lawrence, Tetrahedron Lett. 30, 7341-7344 (1989)) 138 mg, 0.2 mmol) was added, and the mixture was cooled to 0 ° C. under argon gas. Next, N-bromosuccinimide (NBS) (42.7 mg, 0.24 mmol) was added and stirred for 1 hour. The reaction solution was washed with saturated sodium bicarbonate. The organic layer was dried over anhydrous sodium sulfate and purified using a silica gel column (solvent: CH ₂ Cl ₂ ) to remove the solvent. The solid was added to CHCl ₃ (100 mL) and bubbled with argon gas for 5 minutes. Then, a saturated zinc acetate methanol solution (5 mL) was added, and the mixture was refluxed for 1 hour under argon gas. A saturated aqueous sodium hydrogen carbonate solution was added to the mixed solution for liquid separation, and the organic layer was purified with a silica gel column (solvent CH ₂ Cl ₂ ). Using GPC / HPLC, starting material (22 mg, 15%), Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-bromoporphyrin (119 mg, 72%), 5 , 15-di (3,5-t-butylphenyl) -10,20-dibromoporphyrin (14.5 mg, 8%).

The NMR, UV / Vis, and MS spectrum data of the obtained Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-bromoporphyrin are shown below.
・¹ H-NMR (CDC13): 1.57 (s, 36H, t-butyl), 7.84 (t, J = 2 Hz, 2H, Ar), 8.09 (d, J = 2 Hz, 4H, Ar), 9.10 (d, J = 5.0 Hz, 2H, Por-b), 9.11 (d, J = 5.0 Hz, 2H, Por-b), 9.38 (d, J = 5.0 Hz, 2H, Por-b), 9.83 (d, J = 5.0 Hz, 2H, Por-b), 10.24 (s, 1H, meso);
FAB MS found m / z 828.3, Calcd for m / z 828.3;
UV / Vis (CH2C12): 417 (Soret), 513, 549, 590, and 537 nm.

(Production of Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-phenylporphyrin)
The obtained Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-bromoporphyrin (100 mg, 0.12 mmol) was dissolved in toluene (40 mL), and dihydroxyphenylborane (167 mg, 1.2 mmol), sodium iodide (176 mg, 1.2 mmol), and tetrakis (triphenylphosphine) palladium (0) (10.5 mg, 0.06 mmol) were added, freeze degassing three times, and argon gas for 5 hours. The mixture was stirred under reflux with heating. The reaction solution was washed with distilled water, and the organic layer was dried over anhydrous sodium sulfate. The reaction solution was purified by a silica gel column (solvent: CH ₂ Cl ₂ ), and the solvent was removed. The solid was recrystallized from CHCl ₃ / CH ₃ CN to obtain Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-phenylporphyrin (71.2 mg, 0.086 mmol).

The NMR, UV / Vis, and MS spectrum data of the obtained Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-phenylporphyrin are shown below.
・¹ H-NMR (CDC13): 1.57 (s, 36H, t-butyl), 7.76 (m, 3H, Ar), 7,84 (t, J = 2Hz, 2H, Ar), 8.14 (d, J = 2Hz, 2H, Ar), 8.24 (d, J = 6Hz, 2H, Ar), 8.99 (d, J = 5.0 Hz, 2H, Por-b), 9.06 (d, J = 5.0 Hz, 2H, Por-b ), 9.17 (d, J = 5.0 Hz, 2H, Por-b), 9.43 (d, J = 5.0 Hz, 2H, Por-b), 10.29 (s, 1H, meso);
FAB MS found m / z 828.3, Calcd for m / z 828.3;
UV / Vis (CH2C12): 415 (Soret) and 543nm.

(Production of Zn (II) -meso-meso-linked porphyrin dimer)
The obtained Zn (II) 5, 15-di (3,5-t-butylphenyl) -10-phenylporphyrin (71.2 mg, 0.086 mmol) was dissolved in CHCl ₃ (300 mL). A 0.1 MAgPF ₆ acetonitrile solution (0.09 mmol) was added, and the mixture was stirred at 60 ° C for 5 hours with heating under reflux. The reaction solution was washed with a saturated aqueous sodium hydrogen carbonate solution, and the organic layer was dried over anhydrous sodium sulfate. Zn (II) -meso-meso linked porphyrin dimer (62 mg, 0.037 mmol) and raw material (8 mg, 0.009 mmol) were separated using GPC / HPLC.

The NMR, UV / Vis, and MS spectrum data of the obtained Zn (II) -meso-meso-linked porphyrin dimer are shown below.
・¹ H-NMR (CDC13): 1.44 (s, 36H, t-butyl), 7.70 (s, 4H, Ar), 7,80 (m, 6H, Ar), 8.09 (d, J = 2Hz, 8H, Ar), 8.14 (d, J = 5Hz, 4H, Ar), 8.32 (d, J = 7.0 Hz, 4H, Por-b), 8.72 (d, J = 5.0 Hz, 4H, Por-b), 9.03 ( s, 1H, meso);
FAB MS found m / z 1650.1, Calcd for m / z 1650.1;
UV / Vis (CH2C12): 419 (Soret), 455, 559, and 597 nm.

(Production of Zn (II) -fused porphyrin dimer (compound (4)))
Obtained Zn (II) -meso-meso-linked porphyrin dimer (62 mg, 0.037 mmol), scandium triflate (91 mg, 0.19 mmol), DDQ (42 mg, 0.19 mmol) in toluene (20 mL) In addition, the mixture was stirred for 30 minutes under reflux with heating under argon gas. THF (10 mL) was added to the reaction solution, and the mixture was further stirred for 5 minutes. The reaction solution was purified with an alumina column (solvent: THF), and the solvent was removed to obtain a solid. The solid was recrystallized from CHCl ₃ / CH ₃ CN to obtain Zn (II) -fused porphyrin dimer (48 mg, 0.026 mmol), which is compound (4).

The NMR, UV / Vis, and MS spectrum data of the obtained compound (4), Zn (II) -fused porphyrin dimer, are shown below.
・¹ H NMR (CDCl ₃ ): 1.45 (s, 72H, t-Bu), 7.35 (s, 4H, Por-b), 7.56 (d, J) 4.9 Hz, 4H, Por-b), 7.62 (t , J = 1.8 Hz, 4H, Ar- H), 7.66 (d, J = 1.8 Hz, 8H, Ar-H), 7.69 (s, 10H, Ar-H), and 7.80 (d, J = 4.9 Hz, 4H, Por-b);
HRMS (FAB) found m / z 1642.67 (3), calcd for m / z 1642.7123;
UV / Vis (CHCl3) 418 (10 800), 581 (91 000), and 1068 (19 700) nm.

[Synthesis of Compound (5)]
(Production of condensed ring porphyrin dimer)
Zn (II) -fused porphyrin dimer (30 mg, 0.018 mmol), which is the above compound (4), was dissolved in CHCl ₃ , concentrated sulfuric acid (1 mL) was added, and the mixture was stirred for 5 minutes. The reaction solution was neutralized and washed with a saturated aqueous sodium bicarbonate solution. The organic layer was purified using a silica gel column (CH ₂ Cl ₂ ) to remove the solvent and obtain a solid. The solid was recrystallized from CHCl ₃ / CH ₃ CN to obtain a condensed ring porphyrin dimer (25 mg, 0.016 mmol).

The NMR, UV / Vis, and MS spectrum data of the obtained condensed ring porphyrin dimer are shown below.
・¹ H NMR (CDCl ₃ ): 1.45 (s, 72H, t-Bu), 1.51 (s, 4H, NH), 7.55 (d, J = 4.9 Hz, 4H, Por-b), 7.56 (s, 4H , Por-b), 7.58 (s, 10H, Ar-H), 7.62 (t, J = 1.8 Hz, 4H, Ar-H), 7.64 (d, J = 1.8 Hz, 8H, Ar-H), and 7.79 (d, J = 4.9 Hz, 4H, Por-b).
HRMS (FAB) found m / z 1518.91 (7), calcd m / z 1518.8853;
UV / Vis (CHCl3) 410 (119 300), 567 (114 400), and 1086 (26 100) nm.

(Production of Cu (II) -fused porphyrin dimer)
The obtained condensed ring porphyrin dimer (20 mg, 0.013 mmol) was added to CHCl ₃ (100 mL), and bubbled with argon gas for 5 minutes. Saturated copper acetate methanol solution (5 ml) was added, and the mixture was stirred with heating under reflux for 1 hr. The reaction solution was washed with a saturated aqueous sodium hydrogen carbonate solution, the organic layer was purified with a silica gel column (CH ₂ Cl ₂ ), the solvent was removed, and the Cu (II) -fused porphyrin dimer (18 mg, 0.01 mmol) Got.

The UV / Vis and MS spectrum data of the obtained Cu (II) -fused porphyrin dimer are shown below.
HRMS (FAB) found m / z 1640.71 (5), calcd for m / z 1640.7332;
UV / Vis (CHCl ₃ ) 411 (161 800), 575 (136 100), and 994 (38 700) nm.

[Synthesis of Compound (6)]
(Production of 4-dodecyloxybenzaldehyde)
4-Hydroxybenzaldehyde (7.32 g, 0.06 mol) was stirred with 1-bromododecane (12.5 g) and potassium carbonate (10 g) in acetone (300 ml) for 6 hours under heating and reflux. The reaction solution was returned to room temperature, diluted with distilled water, and extracted with ether. The organic layer was dried over anhydrous sodium sulfate and the solvent was removed to give a yellow oil. The yellow oil was purified with a silica gel column (benzene; hexane = 1: 9) to obtain 4-dodecyloxybenzaldehyde (4.6 g, 14.6 mmol).

The NMR spectrum data of the obtained 4-dodecyloxybenzaldehyde is shown below.
・ 'H-NMR (CDC13) 0.86 (7.0 Hz, 3H, alkyl), 1.24 (m, 18H, alkyl), 1.44 (m, 2H, alkyl), 1.77 (m, 2H, alkyl), 4.01 (t, 2H ), 6.96 (d, J = 8.5 Hz, 2H, Ar), 7.79 (d, J = 8.5 Hz, 2H, Ar), 9.86 (s, 1H, aldehyde).

(Manufacture of 2, 2'-dipyrromethane)
2,2′-dipyrromethane was produced according to the method described in Tetrahedron Letters, 2000, 41, 4609 (Lee, et al.).

(Production of 5, 15-bis (4-dodecyloxyphenyl) porphyrin)
In CH ₂ Cl ₂ (500 mL), add the obtained 2, 2'-dipyrromethane (1.49 g, 10.3 mmol) and 4-dodecyloxybenzaldehyde (3.26 g, 10.3 mmol), and bubble with argon gas for 5 min. did. Trifluoroacetic acid (7.3 mmol) was added under Ar2 and stirred at room temperature for 2 hours. DDQ (3.70 g, 16.3 mmol) was added to the reaction solution, and the mixture was further stirred for 1 hour. Triethylamine (1 mL) was added to the reaction solution, which was purified by an alumina column (CH ₂ Cl ₂ ), and the solvent was removed to obtain 5,15-bis (4-dodecyloxyphenyl) porphyrin (1000 mg).

The NMR, UV / Vis, and MS spectrum data of the obtained 5,15-bis (4-dodecyloxyphenyl) porphyrin are shown below.
1H-NMR (CDCl ₃ ) -3.08 (s, 2H, NH), 0.90 (t, J = 7.0 Hz, 6H, alkyl), 1.23-1.41 (m, 32H, alkyl), 1.63 (m, 4H), 2.00 (m, 4H, alkyl), 4.26 (t, 4H), 7.33 (d, J = 8.5 Hz, 4H, Ar), 8.16 (d, J = 8.5 Hz, 4H, Ar), 9.11 (d, J = 5.0 Hz, 4H b), 9.38 (d, J = 5.0 Hz, 4H b), and 10.28 (s, 2H, meso).
FAB MS found m / z 829, calcd for m / z 829;
UV / Vis (CHCl3): 409, 505, 540, 575, and 631 nm.

(Production of Zn (II) -5, 15-bis (4-dodecyloxyphenyl) porphyrin)
The resulting 5,15-bis (4-dodecyloxyphenyl) porphyrin (710 mg, 0.80 mmol) was added to CHCl ₃ (100 mL), and bubbled with argon for 5 minutes. Saturated zinc acetate in methanol (5 ml) was added, and the mixture was stirred with heating under reflux for 1 hr. The reaction solution was washed with a saturated aqueous sodium hydrogen carbonate solution, and the organic layer was purified with a silica gel column (CH ₂ Cl ₂ ). The solvent was removed to obtain 5,15-bis (4-dodecyloxyphenyl) Zn (II) -porphyrin (680 mg, 0.76 mmol).

The NMR, UV / Vis, and MS spectrum data of the obtained 5,15-bis (4-dodecyloxyphenyl) Zn (II) -porphyrin are shown below.
・¹ H-NMR (CDC1 ₃ ) .0.90 (t, J = 7.0 Hz, 6H, alkyl), 1.23-1.51 (m, 32H, alkyl), 1.64 (m, 4H), 2.01 (m, 4H, alkyl) , 4.28 (t, 4H), 7.30 (d, J = 8.5 Hz, 4H, Ar), 8.14 (d, J = 8.5 Hz, 4H, Ar), 9.16 (d, J = 5.0 Hz, 4H,), 9.41 (d, / = 5.0 Hz, 4H), and 10.28 (s, 2H, meso).
FAB MS found m / z 893, calcd for m / z 893;
UV / Vis (CHC13): 409 (Soret) and 537 nm.

(Production of meso-meso-linked porphyrin trimer)
The obtained 5,15-bis (4-dodecyloxyphenyl) Zn (II) -porphyrin (420 mg, 0.47 mmol) was dissolved in CHCl ₃ (300 mL), and 0.1M AgPF ₆ acetonitrile solution (0.24 mmol) was added. And stirred at room temperature for 5 hours. A saturated aqueous sodium hydrogen carbonate solution was added to the reaction solution for washing, and the organic layer was dried over anhydrous sodium sulfate. Using GPC / HPLC, monomer (170 mg, 40%), dimer (95 mg, 23%), trimer (30 mg, 8%), tetramer (8 mg, 2%) Got.

The NMR and MS spectrum data of the resulting trimer are shown below.
・¹ H-NMR (CDC1 ₃ ) 0.78 (t, J = 7.0 Hz, 6H, alkyl), 0.87 (t, J = 7.0 Hz, 12H, alkyl), 1.17-1.48 (broad-m, 108H, alkyl), 1.78 (m, 4H, alkyl), 1.93 (m, 8H, alkyl), 4.03 (t, 4H, alkyl), 4.19 (t, 8H, alkyl), 7.06 (d, 4H, Ar), 7.22 (d, 8H , Ar), 8.09 (d, 4H, Ar), 8.16 (d, J = 5.0 Hz, 8H, Ar), 8.14 (d, 4H, por-b), 8.25 (d, 4H, por-b), 8.72 (d, J = 5.0 Hz, 4H, Por-b), 8.81 (d, / = 5.0 Hz, 4H, Por-b), 9.20 (d, J = 5.0 Hz, 4H, Por-b), 9.48 (d , J = 5.0 Hz, 4H, Por-b), 10.34 (s, 2H, meso).
MALDI-TOF MS found m / z 2677, calcd m / z 2677.

(Phenyl cap to meso-meso-linked porphyrin trimer)
To CHCl ₃ (100 mL), meso-meso linked porphyrin trimer (200 mg, 0.074 mmol) was added and cooled to 0 ° C. under argon gas. Thereto, 2.4 equivalents of N-bromosuccinimide (NBS) was added and stirred for 10 minutes. The mixed solution was quenched with 5 mL of acetone. After stirring for 5 minutes, CHCl ₃ and saturated aqueous sodium hydrogen carbonate solution were added to separate the layers. The organic layer was dried over anhydrous sodium sulfate and purified with a silica gel column (CH ₂ Cl ₂ ).
The purified solid was dissolved in toluene (30 mL) and dihydroxyphenylborane (117 mg, 0.84 mmol), sodium iodide (117 mg, 0.84 mmol), tetrakis (triphenylphosphine) palladium (0) (7 mg, 0.04 mmol). ) Was added. The reaction solution was freeze-degassed three times and stirred under reflux with heating under argon for 5 hours. The reaction solution was washed with distilled water, and the organic layer was dried over sodium sulfate. The reaction solution was purified with a silica gel column (CH ₂ Cl ₂ ), and the solvent was removed. The solid was recrystallized from CHCl ₃ / CH ₃ CN. And the meso-meso coupling | bonding porphyrin trimer (160.1 mg, 0.056 mmol) by which the meso position was phenyl-capped was obtained.

The NMR, UV / Vis, and MS spectrum data of the obtained meso-meso-linked porphyrin trimer with a meso-position phenyl-capped are shown below.
・¹ H-NMR (CDC1 ₃ ) 0.79-0.88 (m, 18H, alkyl), 1.17-1.50 (broad-m, 100H, alkyl), 1.56 (m, 8H, alkyl), 1.80 (m, 4H, alkyl) , 1.92 (m, 8H, alkyl), 4.05 (t, 4H, alkyl), 4.18 (t, 8H, alkyl), 7.08 (d, 4H, Ar), 7.20 (d, 8H, Ar), 7.81 (broad- m, 6H, Ph), 8.10 (d, 4H, Ar), 8.14 (d, 8H, Ar), 8.18 (d, 4H, por-b), 8.23 (d, 4H, por-b), 8.32 (d , 4H, Ph), 8.74 (d, 4H, Por--b), 8.77 (d, 4H, por), 9.02 (d, 4H, Por--b), and 9.05 (d, 4H, Por-b) .
MALDI-TOF MS found m / z 2827; calcd for 2828;
UV / Vis (CHC13): 419, 478, and 570 nm.

(Production of condensed porphyrin trimer (compound (6)))
The resulting meta-phenyl-capped meso-meso-linked porphyrin trimer (19 mg, 6.7 μmol), scandium triflate (33 mg, 0.7 mmol), and DDQ (15 mg, 0.7 mmol) in 30 mL In addition to toluene, the mixture was stirred for 30 minutes under heating and refluxing under argon gas. THF (10 mL) was added to the reaction solution, and the mixture was further stirred for 5 minutes, purified by an alumina column (THF), the solvent was removed, and a solid was obtained. The solid was recrystallized from CHCl ₃ / CH ₃ CN to obtain a condensed ring porphyrin trimer (compound (6)) (12 mg, yieldl, 64%).

The UV / Vis and MS spectrum data of the obtained condensed ring porphyrin trimer (compound (6)) are shown below.
MALDI-TOF MS found m / z 2818, calcd m / z 2820;
UV / Vis (CHC13): 414, 672, and 1324 nm.

[Evaluation of two-photon absorption cross section]
Each compound obtained by the above method was measured by the following method. The results are shown in Table 1 in GM units.
The two-photon absorption cross section is evaluated by Guang S. He, Lixiang Yuan, Ning Cheng, Jayant D. Bhawalkar, Paras N. Prasad, Lawrence L. Brott, Stephen J. Clarson, Bruce A. Reinhardt, J. Opt. Soc. Am. B Vol.14, No.5 (1997) pp. 1079-1087 A schematic diagram of the measurement system is shown in FIG.
In addition, "laser" in FIG. 1 is a titanium sapphire laser, and used Integra made by Quantronix. “PD” means a photo detector, and Newport Co., Ltd .: cylindrical detector MODEL 818-SL was used. Furthermore, “Amp.” Means an amplifier, manufactured by Stanford Research Systems (STANFORD RESEARCH SYSTEMS): LOW-NOISE CURRENT PREAMPLIFIER MODEL SR570 and Gated Integrator & Box Car Averager (GATED INTEGRATOR & BOXCAR AVERAGER) MODEL SR250 was used. “BS” means a beam splitter, and “Quarts cell” means a quartz sample cell. Further, “PC” means a personal computer.

A femtosecond titanium sapphire laser (wavelength: 800 nm, pulse width: 120 fs, repetition rate: 1 kHz, average output: 2 W, intensity: 2 mJ / pulse, beam diameter: 10 mmφ, peak power: 20 GW) was used as a measurement light source. Part of the laser output (hereinafter referred to as reference light) was branched by a BS (beam splitter), and the intensity was measured by a PD (photo detector) to correct fluctuations in incident light intensity. The remainder of the laser output was attenuated to about 10 mW by an ND filter and then condensed by a condenser lens. A quartz cell (optical path length: 10 mm) filled with the sample solution was placed in the condensed optical path portion, and the position was moved along the optical path to perform Z-scan measurement. Thus changing the excitation light density in the range of ^{1GW / cm 2 ~40GW / cm 2} .

The measurement sample was prepared as follows.
-Example 1 ... 0.02 mM compound (4) in toluene solution-Example 2 ... 0.02 mM compound (5) in toluene solution-Example 3 ... 0.02 mM compound (6) in toluene solution

  Further, a quartz cell having an optical path length of 10 mm was used as the sample cell. Laser light transmitted through the sample cell (hereinafter referred to as transmitted light) was appropriately attenuated by an ND filter, passed through a colored glass filter such as R72, and the intensity was measured by a photodetector. This measurement was performed for a plurality of excitation light densities, and the normalized solution transmitted light intensity was obtained by dividing the transmitted light intensity by the reference light intensity.

  In the same measurement arrangement, the sample cell was filled with only the solvent, the same measurement was performed, and the normalized solvent transmitted light intensity was obtained. Further, the transmittance was determined by dividing the normalized solution transmitted light intensity by the normalized solvent transmitted light intensity.

The dependence of the transmittance on the excitation light density was measured by the procedure as described above, and the result was fitted by the theoretical formula (i) described in the above document to obtain the nonlinear absorption coefficient.
Ti = [ln (1 + I ₀ L ₀ β)] / I ₀ L ₀ β (i)
(In the formula, Ti represents transmittance (%), I ₀ represents excitation light density [GW / cm ² ], L ₀ represents sample cell length [cm], and β represents nonlinear absorption coefficient [cm / GW].)

From this nonlinear absorption coefficient, the two-photon absorption cross section δ was determined by the following equation (ii). (The unit of δ is 1GM = 1 × 10 ⁻⁵⁰ cm ⁴ · s · photon ⁻¹ .)
_{δ = 1000 × hνβ / N A} C (ii)
(In the above formula, h is Planck's constant [J · s], ν is the frequency [s−1] of the incident laser beam, N _A is the Avogadro number, and C is the solution concentration [mol / L].)

Schematic diagram of measurement system used in evaluation of two-photon absorption cross section

Claims (1)

A two-photon absorption material mainly comprising a compound according to the following formula (1) or (2).

(In the above formulas (1) and (2), Ar represents a substituent having an aromatic ring. Further, M represents a transition metal ion. Furthermore, each Ar may be different.)

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