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Volumn 131, Issue 51, 2009, Pages 18386-18392

Laterally azo-bridged H-shaped ferroelectric dimesogens for second-order nonlinear optics: Ferroelectricity and second harmonic generation

Author keywords

[No Author keywords available]

Indexed keywords

1064 NM; CALAMITICS; DISPERSE RED 1; ELECTRO-OPTICAL; FERROELECTRIC LIQUID CRYSTAL; H-SHAPED; INCIDENT WAVELENGTH; NONLINEAR COEFFICIENT; POLARIZED LIGHT MICROSCOPY; SECOND HARMONIC GENERATION; SECOND ORDER NONLINEAR OPTICS; THERMODYNAMICALLY STABLE;

EID: 73249150927     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9069166     Document Type: Article
Times cited : (36)

References (58)
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    • Nalwa, H. S, Miyata, S, Eds, CRC Press, Inc: Boca Raton, FL
    • (c) Nonlinear optics of organic molecules and polymers; Nalwa, H. S., Miyata, S., Eds.; CRC Press, Inc: Boca Raton, FL, 1996.
    • (1996) Nonlinear optics of organic molecules and polymers
  • 11
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    • Although polymeric nematic liquid crystals have been shown to possess permanent polar order and strong SHG activity, they cannot respond to the applied electric field as well as FLCs owing to the high viscosity of polymers: (a) Watanabe, T, Miyata, S, Furakawa, T, Takezoe, H, Nishi, T, Migita, A, Sone, M, Watanabe, J. Jpn. J. Appl. Phys. 1996, 35, L505
    • Although polymeric nematic liquid crystals have been shown to possess permanent polar order and strong SHG activity, they cannot respond to the applied electric field as well as FLCs owing to the high viscosity of polymers: (a) Watanabe, T.; Miyata, S.; Furakawa, T.; Takezoe, H.; Nishi, T.; Migita, A.; Sone, M.; Watanabe, J. Jpn. J. Appl. Phys. 1996, 35, L505.
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    • Demus, D, Goodby, J. W, Gray, G. W, Spiess, H. W, Vill, V, Eds, Wiley-VCH: Weinheim, Germany
    • (c) Dubois, J.-C.; Barny, P. L.; Mauzac, M.; Noel, C. In Handbook of Liquid Crystals; Demus, D., Goodby, J. W., Gray, G. W., Spiess, H. W., Vill, V., Eds.; Wiley-VCH: Weinheim, Germany, 1998; Vol. 3, p 207.
    • (1998) Handbook of Liquid Crystals , vol.3 , pp. 207
    • Dubois, J.-C.1    Barny, P.L.2    Mauzac, M.3    Noel, C.4
  • 28
    • 0012200165 scopus 로고    scopus 로고
    • 3 should be used instead of 1.4 g mentioned in the experimental procedure of this reference.
    • 3 should be used instead of 1.4 g mentioned in the experimental procedure of this reference.
  • 31
    • 73249132497 scopus 로고    scopus 로고
    • The synthesis of 2c involved sequential addition of 4′-decyloxy-4-biphenylcarboxylic acid chloride and 4′-(11- undecenyloxy)-4-biphenylcarboxylic acid chloride, respectively by utilizing the regioselectivity due to the nitro group.
    • The synthesis of 2c involved sequential addition of 4′-decyloxy-4-biphenylcarboxylic acid chloride and 4′-(11- undecenyloxy)-4-biphenylcarboxylic acid chloride, respectively by utilizing the regioselectivity due to the nitro group.
  • 33
    • 73249137021 scopus 로고    scopus 로고
    • The first peak in 1d was attributed to a transition from the first crystalline state to the second crystalline state, and the second peak was assigned as a transition from the second crystalline state to the SmC* phase. See DSC data in Table 1.
    • The first peak in 1d was attributed to a transition from the first crystalline state to the second crystalline state, and the second peak was assigned as a transition from the second crystalline state to the SmC* phase. See DSC data in Table 1.
  • 35
    • 73249118807 scopus 로고    scopus 로고
    • The calculated molecular length for 1c from the MOPAC molecular modeling is 4.4 nm on the basis of the rod with the azo group meta to the chiral center.
    • The calculated molecular length for 1c from the MOPAC molecular modeling is 4.4 nm on the basis of the rod with the azo group meta to the chiral center.
  • 36
    • 73249115899 scopus 로고    scopus 로고
    • The optical tilt angle was measured at 140 °C in an aligned 1.2 μm cell with nylon alignment layers upon the application of a SW voltage (±10 V, 10 Hz) and kept almost a constant value of 22° when the temperature was decreased from 140 to 100 °C.
    • The optical tilt angle was measured at 140 °C in an aligned 1.2 μm cell with nylon alignment layers upon the application of a SW voltage (±10 V, 10 Hz) and kept almost a constant value of 22° when the temperature was decreased from 140 to 100 °C.
  • 37
    • 73249146570 scopus 로고    scopus 로고
    • Crystallization was observed when cells were stored at room temperature for several days (e.g., 2a) or several weeks (e.g., 2c). In addition, a large endothermic peak due to a transition from the crystalline state to the SmC* phase was observed during the first heating cycle of a DSC scan when the samples were stored at room temperature for months, but the same peak could not be observed if the samples were stored at room temperature for a short time. These observations strongly indicate that crystallization from the glassy state takes place slowly during storage of samples.
    • Crystallization was observed when cells were stored at room temperature for several days (e.g., 2a) or several weeks (e.g., 2c). In addition, a large endothermic peak due to a transition from the crystalline state to the SmC* phase was observed during the first heating cycle of a DSC scan when the samples were stored at room temperature for months, but the same peak could not be observed if the samples were stored at room temperature for a short time. These observations strongly indicate that crystallization from the glassy state takes place slowly during storage of samples.
  • 38
    • 73249119865 scopus 로고    scopus 로고
    • Conventional rod-shaped FLCs' switching speed is 10-150 μs.
    • Conventional rod-shaped FLCs' switching speed is 10-150 μs.
  • 39
    • 73249129345 scopus 로고    scopus 로고
    • The optical tilt angle was measured at 60 °C in an aligned 1.2 μm cell with nylon alignment layers upon the application of a SW voltage (±20 V, 10 Hz).
    • The optical tilt angle was measured at 60 °C in an aligned 1.2 μm cell with nylon alignment layers upon the application of a SW voltage (±20 V, 10 Hz).
  • 40
    • 73249124281 scopus 로고    scopus 로고
    • L is the sum (3.99 nm) of the molecular length (3.75 nm) from the MOPAC molecular modeling and van der Waals diameter (0.24 nm) of an H atom.
    • L is the sum (3.99 nm) of the molecular length (3.75 nm) from the MOPAC molecular modeling and van der Waals diameter (0.24 nm) of an H atom.
  • 41
    • 73249134475 scopus 로고    scopus 로고
    • A* phase in ref 14, p 124.
    • A* phase in ref 14, p 124.
  • 42
    • 73249150216 scopus 로고    scopus 로고
    • Cell surfaces were treated with n-octadecyltriethoxysilane to form self-assembled monolayers to achieve homeotropic alignment.
    • Cell surfaces were treated with n-octadecyltriethoxysilane to form self-assembled monolayers to achieve homeotropic alignment.
  • 45
    • 73249140473 scopus 로고    scopus 로고
    • The SHG signal at 532 nm generated from the incident beam (λ = 1064 nm) is almost entirely absorbed by 2a-c. Absorption can be significantly reduced by using a small percentage of 2a-c.
    • The SHG signal at 532 nm generated from the incident beam (λ = 1064 nm) is almost entirely absorbed by 2a-c. Absorption can be significantly reduced by using a small percentage of 2a-c.
  • 46
    • 73249124493 scopus 로고    scopus 로고
    • The C-chains might be strongly folded at high temperature due to the special H-shape of the molecules and gradually stretch with decreasing temperature
    • The C-chains might be strongly folded at high temperature due to the special H-shape of the molecules and gradually stretch with decreasing temperature.
  • 49
    • 0032836018 scopus 로고    scopus 로고
    • Dalton et al. have shown that dipole-dipole interaction significantly increases with increased chromophore loading for strong chromophores, but the electro-optical coefficients for polymeric materials, including DR-1 chromophores, are almost linear with chromophore loading if the chromophore density is less than 25 wt, Dalton, L. R, Steier, W. H, Robinson, B. H, Zhang, C, Ren, A, Garner, S, Chen, A, Londergan, T, Irwin, L, Carlson, B, Fifield, L, Phelan, G, Kincaid, C, Amend, J, Jen, A. J. Mater. Chem. 1999, 9, 1905-1920. The DR-1 chromophore density in 2c is 23 wt, Moreover, we have found that 1c and 2c have similar degrees of polar order ∼20, see details in Table S1, Hence, extrapolating the d22 coefficient of 2c from mixtures M1 and M2 is valid
    • 22 coefficient of 2c from mixtures M1 and M2 is valid.
  • 50
    • 73249131684 scopus 로고    scopus 로고
    • 22 value of 4.5 pm/V, which is still remarkable for calamitic FLCs. This result, together with SHG measurements of mixtures M1 and M2 at the same wavelength, will be published separately.
    • 22 value of 4.5 pm/V, which is still remarkable for calamitic FLCs. This result, together with SHG measurements of mixtures M1 and M2 at the same wavelength, will be published separately.
  • 52
    • 3343002793 scopus 로고    scopus 로고
    • -30 esu): Cheng, L. T.; Tam, W.; Stevenson, S. H.; Meredith, G. R.; Rikken, G.; Marder, S. R. J. Phys. Chem. 1991, 95, 10631-10643.
    • -30 esu): Cheng, L. T.; Tam, W.; Stevenson, S. H.; Meredith, G. R.; Rikken, G.; Marder, S. R. J. Phys. Chem. 1991, 95, 10631-10643.
  • 53
    • 33845185367 scopus 로고    scopus 로고
    • Their dispersion-free values β0 (35.2 vs 7.6 x 10-30 esu) are extrapolated using the two-level model: Spackman, M. A. J. Phys. Chem. 1989, 93, 7594. Furthermore, the degree of polar order for Roche-1 (∼30, see ref 6a) is only 50% larger than that (∼20, see Table S1) for 2c. Taking these factors into account, a large d22 value (17 pm/V) for 2c is reasonable
    • 22 value (17 pm/V) for 2c is reasonable.
  • 57
    • 45449106014 scopus 로고    scopus 로고
    • Note that big differences for d coefficients of similar bent-core compounds were reported by different groups, and the reasons are still unclear
    • (d) Etxebarria, J.; Ros, M. B. J. Mater. Chem. 2008, 18, 2919-2916. Note that big differences for d coefficients of similar bent-core compounds were reported by different groups, and the reasons are still unclear.
    • (2008) J. Mater. Chem , vol.18 , pp. 2919-2916
    • Etxebarria, J.1    Ros, M.B.2
  • 58
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    • 22 value for 2c should be larger than 5 pm/V.
    • 22 value for 2c should be larger than 5 pm/V.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.