Novel fluorinated ferroelectric organosiloxane liquid crystals

Article abstract of DOI:10.1080/15421406.2011.570148

A progress report on the synthesis and characterisation of a series of fluorinated chiral bi-mesogen low molar mass organosiloxane materials is presented. The mesogenic moiety is identical to that in the TSiKN65F mono-mesogen material reported by Naciri et al., which displays a de Vries-type SmA* phase. The parameter varied across the series is the length of the alkyl chain linking the mesogen moiety to the siloxane. The material with 10 carbon atoms in the chains displays a stable smectic phase with ferroelectric response at room temperature, whereas the materials with 6, 7 and 8 carbon atoms tend to crystallize. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15421406.2011.570148

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Novel Fluorinated Ferroelectric
Organosiloxane Liquid Crystals
W. M. Zoghaib a , C. Carboni b , A. K. George b , S. AL-Manthari a , A.
Al-Hussaini a & F. Al-Futaisi a
a Chemistry Department, Sultan Qaboos University, Al-Khod, Oman
b Physics Department, Sultan Qaboos University, Al-Khod, Oman
Published online: 14 Jun 2011.
To cite this article: W. M. Zoghaib , C. Carboni , A. K. George , S. AL-Manthari , A. Al-Hussaini & F. Al-
Futaisi (2011): Novel Fluorinated Ferroelectric Organosiloxane Liquid Crystals, Molecular Crystals and
Liquid Crystals, 542:1, 123/[645]-131/[653]
To link to this article: http://dx.doi.org/10.1080/15421406.2011.570148
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Mol. Cryst. Liq. Cryst., Vol. 542: pp. 123=[645]–131=[653], 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080/15421406.2011.570148
Novel Fluorinated Ferroelectric Organosiloxane
Liquid Crystals
W. M. ZOGHAIB,1 C. CARBONI,2 A. K. GEORGE,2
S. AL-MANTHARI,1 A. AL-HUSSAINI,1 AND
F. AL-FUTAISI1
1Chemistry Department, Sultan Qaboos University, Al-Khod, Oman
2Physics Department, Sultan Qaboos University, Al-Khod, Oman
A progress report on the synthesis and characterisation of a series of fluorinated
chiral bi-mesogen low molar mass organosiloxane materials is presented. The meso-
genic moiety is identical to that in the TSiKN65F mono-mesogen material reported
by Naciri et al., which displays a de Vries-type SmAꢀ phase. The parameter varied
across the series is the length of the alkyl chain linking the mesogen moiety to the
siloxane. The material with 10 carbon atoms in the chains displays a stable smectic
phase with ferroelectric response at room temperature, whereas the materials with 6,
7 and 8 carbon atoms tend to crystallize.
Keywords bi-mesogen; de-Vries phase; ferroelectric; organosiloxane; smectic;
synthesis; trimer
1. Introduction
Low molar mass organosiloxane liquid crystal materials are good candidates for the
search of materials displaying de-Vries type phases [1–6]. The mono-mesogenic
materials TSiKN65 described in references [1–3] displays a transition between
de-Vries SmAꢀ phase to SmCꢀ phase. The fluorinated homologue TSiKN65F
material remains in the de-Vries SmAꢀ phase over the entire temperature range of
the smectic phase [4] indicating that the fluorine stabilizes the de-Vries phase. In
the present work bi-mesogen homologues of TSiKN65F are investigated. Bi
mesogens present additional interesting properties, According to the molecular con-
formation the material can respond to an electric fields as a ferroelectric or an
anti-ferroelectric material [7]. To our knowledge there have been no reports of
de-Vries phases with bi-mesogens. This paper is a progress report on this ongoing
work as presented at the 23rd International Liquid Crystal Conference (ILCC) in
Krakow 2010.
Address correspondence to W. M. Zoghaib, Chemistry Department, Sultan Qaboos
University, PO Box 36, Al-Khod 123, Oman. Tel.: þ968-24142472; Fax: þ968-24141469;
E-mail: zoghaibw@squ.edu.om
123=[645]

124=[646]
W. M. Zoghaib et al.
2. Experimental
The general synthetic scheme is summarized in Figure 1.
Figure 1. The general synthetic scheme.

Fluorinated Organosiloxane Liquid Crystals
125=[647]
2.1. Materials
Reagents were purchased from Aldrich and used as received. Diethyl azo dicarbox-
ylate (DEAD) was purchased from ChemHere (Hong Kong) as a 40% solution in
Toluene. The catalyst dichloro dicyclopentadienyl platinum II was purchased from
STREM Chemicals (Massachusetts, USA).
2.2. Methods
Proton Magnetic Resonance (1H-NMR) spectra were acquired and recorded using a
400 MHz AVANCE Bruker NMR spectrometer in CDCl3 or CD3OD. Carbon
Magnetic Resonance (13C-NMR) spectra were recorded at 100 MHz using the same
NMR spectrometer. Chemical shifts (dppm) were recorded in parts per million (ppm)
downfield from TMS (assigned as zero ppm).
Thin layer chromatography (TLC) and preparative TLC were performed on
glass plates pre-coated with Merck silica gel, whereas flash column chromatography
was performed using Merck 60 silica gel purchased from Aldrich.
Rotary evaporator (BUCHI) was used to evaporate solvents at low pressure.
Anhydrous reaction conditions were carried out under an inert atmosphere of dry
Argon. THF was dried by distillation over potassium metal under Argon.
Liquid crystals transition temperatures were identified by polarized light
microscopy in conjunction with a heating stage and a temperature control unit
(Linkam TMS 94).
3. Synthesis
4-Hydroxy-4-biphenylbenzoate (3). Prepared according to known procedure [6]
(70.2% yield).
40-Hydroxy-30-nitro-4-biphenylbenzoate (4). Prepared according to known
procedure [6] (55.4% yield).
40-((R)-1-Methylhexyloxy)-30-nitro-4-biphenylbenzoate (5). Prepared according to
known procedure [6] (87.4% yield).
4-((R)-1-Methylhexyloxy)-3-nitro-4-hydroxybiphenyl (6). Prepared according to
known procedure [6] (70.2% yield).
Methyl-3-Fluoro-4-hydroxybenzoate (8). Prepared according to known procedure
[6] (50.4% yield).
4-(X-Alkenyloxy) Bphenyl-3-fluoro-4-carboxylic Acid Methyl Esters (9). Prepared
according to known procedure [6].
4-(5-Hexenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid Methyl Ester. 94% yield.
1H NMR (400 MHz, CDCl3, TMS) d (ppm): 1.48–1.55 (m, 2H, CH2(11)); 1.78
(m, 2H, CH2(10)); 2.06 (m, 2H, CH2(12)); 3.81 (s, 1H, CH3(1)); 4.01 (t, 2H,
CH2(9), J1 ¼ 6.5, J2 ¼ 6.5); 4.89–4.94 (m, 1H, CH2(14)); 4.94–4.99 (m, 1H,
CH2(15)), 5.75 (m, 1H, CH(14)); 6.88 (t, 1H, ArH(6), J1 ¼ 8.3, J2 ¼ 8.4); 7.64–7.68
(dd, 1H, ArH(4), J1 ¼ 2.0, J2 ¼ 11.7); 7.70–7.73 (m, 1H, ArH(5)).

126=[648]
W. M. Zoghaib et al.
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 25.52 CH2(11), 28.82 CH2(10),
33.73 CH2(12), 69.51 CH3(1), 77.23 CH2(9), 113.75 ArC(4), 115.35 CH2(14),
117.70 ArC(6), 123.04 ArC(3), 126.99 CHþ(6), 138.67CH(13), 151.60 Arc(8), 153.42
=
ArC(7), 166.43 C O(2). EI MS m=z ¼ MI : 252.5 (3%).
4-(6-Heptenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid Methyl Ester. 33.6% yield.
1H NMR (400 MHz, CDCl3, TMS) d (ppm): 1.18–1.23 (m, 2H, CH2(11));
1.39–1.41 (m, 2H, CH2(12)); 1.44–2.04 (m, 2H, CH2(10)); 2.00–2.04 (m, 2H,
CH2(13)); 3.82 (s, 1H, CH3(1)); 4.01 (t, 2H, CH2(9), J1 ¼ 6.6, J2 ¼ 6.5); 4.86–4.89
(m, 1H, CH2(15)); 4.91–4.96 (m, 1H, CH2(15)), 5.69–5.79 (m, 1H, CH (14)); 6.88
(t, 1H, ArH(6), J1 ¼ 8.3, J2 ¼ 8.4); 7.64–7.68 (dd, 1H, ArH(5), J1 ¼ 2.0, J2 ¼ 11.7);
7.70–7.74 (m, 1H, ArH(4)).
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 25.75 CH2(11), 28.94 CH2(12),
29.27 CH2(10), 32.99 CH2(13), 52.48 CH3(1), 69.66 CH2(9), 113.75 ArC(4), 114.95
CH(15,7), 117.58 ArC(3),117.78 ArC(5),þ139.05 CH(14), 151.63 Arc(8), 151.74
=
ArC(6), 166.43 C O(2). EI MS m=z ¼ MI : 266.5 (3%).
4-(7-Octenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid Methyl Ester. 98% yield.
1H NMR (400 MHz, CDCl3) d (ppm): 1.31–1.45 (m, 6H, CH2(11,12,13)), 1.77
(m, 2H, CH2(10)), 1.99 (m, 2H, CH2(14)), 3.81 (s, 3H, CH3(1), 4.01 (t, 2H,
CH2O(9), J1 ¼ 6.5, J2 ¼ 6.5), 4.85–5.96 (m, 2H, CH2 ¼ CH(16)), 5.74 (m, 1H,
CH(15)), 6.88 (t, 1H, ArH(6), J1 ¼ 8.3, J2 ¼ 8.3), 7.64–7.70 (m, 1H, ArH(4)),
7.70–7.75 (m, 1H, ArH(5)).
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 26.11 CH2(11), 29.14 CH2(12),
29.36 CH2(10), 30.09 CH2(13), 34.05 CH2(14), 69.71 CH2(9), 113.78 CH2(16),
113.75 ArC(6), 114.74 CH2(4), 123.11 ArC(3),126.97 ArC(5), 139.32 CH(15),
=
151.76 ArC(8), 1153.47 ArC(7), 166.44 C O(2).
4-(9-Decenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid Methyl Ester. 79%.
1H NMR (CDCL3, TMS) d (ppm): 1.2–2.08 (m, 14H, (CH2)), 3.98 (t, 2H,
=
CH2O), 4.21 (s, 3H, OCH3), 4.83,4.92 (m, 2H, CH CH2), 5.70 (m, 1H, CH CH2),
=
6.95–8.1 (m, 8H, ArH).
4-(X-Alkenyloxy) Biphenyl-3-fluoro-4-carboxylic Acids (10). Prepared according to
known procedure [6].
4-(5-Hexenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid. 53.8% yield.
1H NMR (400 MHz, CDCl3, TMS) d (ppm): 1.19–1.33 (m, 2H, CH2(11)),
1.72–1.78 (m, 2H, CH2(10)), 2.05–2.10 (m, 2H, CH2(12)), 4.04 (t, 2H, CH2(9),
J1 ¼ 8.6.4, J2 ¼ 6.4); 4.70–4.99 (m, 2H, CH2(14)); 5.77 (m, 1H, CH(13)), 7.03 (t,
1H, ArH(6), J1 ¼ 8.4, J2 ¼ 8.4), 7.61 (d, 1H, ArH(5), J ¼ 11.9), 7.71 (d, 1H,
ArH(4), J ¼ 8.4).
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 22.68 CH2(11), 29.73 CH2(10),
31.73 CH2(12), 69.20 CH2(9), 113.65 ArC(4), 114.20 CH(14), 116.84 ArC(6),
122.71 ArC(3), 126.62 ArC(5), 138.64 CH(13), 150.88 ArC(7), 153.42 ArC(8),
=
168.34 C O(2).
4-(6-Heptenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid. 93.8% yield.
1H NMR (400 MHz, CD3OD, TMS) d (ppm): 1.15–1.27 (m, 2H, CH2(11)),
1.41–1.43 (m, 2H, CH2(12)), 1.76–1.82 (m, 2H, CH2(10)), 1.98–2.05 (m, 2H,
CH2(13)), 4.03 (t, 2H, CH2(9), J1 ¼ 6.5, J2 ¼ 6.6); 4.88–4.97 (m, 2H, CH2(15));

Fluorinated Organosiloxane Liquid Crystals
127=[649]
5.70–5.80 (m, 1H, CH(14)), 6.91 (t, 1H, ArH(6), J1 ¼ 8.3, J2 ¼ 8.3), 7.71–7.74 (dd,
1H, ArH(5), J1 ¼ 1.7, J2 ¼ 11.5), 7.79 (d, 1H, ArH(4), J ¼ 8.6).
13C NMR (100 MHz, CD3OD, TMS) d (ppm): 25.75 CH2(11), 28.95 CH2(12),
29.25 CH2(10), 34.00 CH2(13), 69.71 CH2(9), 113.72 CH(4,6,15),114.97 ArC(3,5),
=
127.86 CH(14), 151.01 ArC(8), 1153.47 ArC(7), 171.66 C O(2).
4-(7-Octenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid. 91% yield.
1H NMR (100 MHz, CDCl3, TMS) d (ppm): 1.30–1.45 (m, 6H, CH2(11,12,13)),
1.78 (m, 2H, CH2(10)), 1.99 (m, 2H, CH2(14)), 4.02 (t, 2H, CH2O(9), J1 ¼ 6.6,
J2 ¼ 6.5), 4.85–5.95 (m, 2H, CH2 ¼ CH(16)), 5.75 (m, 1H, CH(15)), 6.90 (t, 1H,
ArH(6), J1 ¼ 8.3, J2 ¼ 8.4), 7.73 (d, 1H, ArH(4), J ¼ 1.9), 7.80 (d, 1H, ArH(5),
J ¼ 1.1).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 25.82 CH2(11), 28.84 CH2(10),
28.98 CH2(13), 29.13 CH2(12), 33.74 CH2(14), 69.38 CH2(9), 113.74 ArC(4,6),
113.78 CH2(16), 139.01 CH(15), 126.71 ArC(5), 150.91 ArC(8), 151.02 ArC(7),
=
153.35 C O(2).
4-(9-Decenyloxy) Biphenyl-3-fluoro-4-carboxylic Acid. 82% yield.
1H NMR (CDCl3, TMS) d (ppm) 1.18–2.1 (m, 14H, (CH2)), 4.02 (t, 2H, CH2O),
=
4.90 (m, 2H, CHCH2), 5.75 (m, 1H, CH CH2), 6.92 to 7.88 (m, 8H, Ar-H).
4-((R)-2-heptyloxy)-3-nitro-4-biphenyl-4-(9-hexenyloxy)-3-fluorobenzoate (11).
Prepared according to modified known procedure [6].
24% yield.
1H NMR (400 MHz, CDCl3, TMS) d (ppm): 0.83 (t, 3H, CH3(1), J1 ¼ 6.9 Hz,
J2 ¼ 7.2 Hz), 1.14–1.26 (m, 10H, CH2(2,3,4,28,29)), 1.31 (d, 3H, CH3(7), J ¼ 6.1),
1.51–1.61 (m, 2H, CH2(5)), 2.06–2.15 (m, 2H, CH2(30)), 4.07 (t, 2H, CH2(27),
=
J1 ¼ 6.5, J2 ¼ 6.5), 4.45 (m, 1H, CH(6)), 4.92–4.97 (dd, 1H, CH CH2(33),
=
J1 ¼ 1.7 Hz, J2 ¼ 9.9 Hz), 5.01 (d, 1H, CH CH2(32), J ¼ 1.7), 5.73–5.80 (m, 2H,
=
CH CH2(31)), 6.97 (t, 1H, ArH(25), J1 ¼ 8.3, J2 ¼ 8.4), 7.06 (d, 1H, ArH(9),
J ¼ 8.9), 7.22 (d, 2H, ArH(17,18), J ¼ 8.6), 7.51 (d, 2H, ArH(15,16), J ¼ 8.6), 7.62
(dd, ArH(11), J1 ¼ 2.3, J2 ¼ 8.7), 7.84 (dd, 1H, ArH(23), J1 ¼ 2.0, J2 ¼ 11.5), 7.90
(d, 1H, ArH(22), J ¼ 9.3), 7.92 (d, 1H, ArH(12), J ¼ 2.3).
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 14.36 CH3(1), 19.97 CH3(7), 22.93
CH2(2), 25.54 CH2(29), 25.35 CH2(4), 33.70 CH2(30), 32.08 CH2(3), 141.62 CH2(31),
36.61 CH2(5), 69.70 CH2(27), 77.60 CH(6), 115.38 ArC(9), 115.38 ArC(22), 117.59
ArC(25), 122.69 ArC(17,18), 124.17 ArC(12,21), 127.82 ArC(23), 128.20
ArC(15,16), 132.27 ArC(13), 132.95 ArC(14), 138.64 ArC(10), 138.64 ArC(11),
113.95 CH(32), 151.06 ArC(19), 151.30 ArC(24), 152.13 ArC(26), 152.36 ArC(8),
=
164.43 C O(20).
4-((R)-2-heptyloxy)-3-nitro-4-biphenyl-4-(9-heptenyloxy)-3-fluorobenzoate (12).
Prepared according to modified known procedure [6].
88% yield.
1H NMR (400 MHz, CDCl3, TMS) d (ppm): 0.76–0.88 (m, 3H, CH3(1)),
1.14–1.30 (m, 10H, CH2(2,3,4,29,30)), 1.31 (d, 3H, CH3(7), J ¼ 6.1), 1.53–1.62 (m,
2H, CH2(5)), 1.71–1.85 (m, 2H, CH2(28)), 2.01–2.07 (m, 2H, CH2(31)), 4.06 (t,
=
2H, CH2(27), J1 ¼ 6.6, J2 ¼ 6.6), 4.48 (m, 1H, CH(6)), 4.88 (d, 1H, CH CH2(33),
=
J ¼ 15.4), 4.94 (dd, 1H, CH CH2(33), J1 ¼ 10.1, J2 ¼ 12.0), 5.76 (m, 1H,
=
CH CH2(32)), 6.97 (t, 1H, ArH(25), J1 ¼ 8.3, J2 ¼ 8.4), 7.06 (d, 1H, ArH(9),

128=[650]
W. M. Zoghaib et al.
J ¼ 8.9), 7.20 (d, 2H, ArH(17,18), J ¼ 7.3), 7.52 (d, 2H, ArH(15,16), J ¼ 8.7), 7.62
(dd, ArH(11), J1 ¼ 2.4, J2 ¼ 8.7), 7.84 (dd, 1H, ArH(23), J1 ¼ 2.0, J2 ¼ 11.5), 7.90
(d, 1H, ArH(22), J ¼ 8.7), 7.93 (d, 1H, ArH(12), J ¼ 2.3).
13C NMR (100 MHz, CDCl3, TMS) d (ppm): 14.47 CH3(1), 19.96 CH3(7), 23.36
CH2(2), 26.80 CH2(29), 29.26 CH2(4), 29.74 CH2(30), 30.08 CH2(28), 30.55 CH2(3),
32.08 CH2(31), 36.61 CH2(5), 69.82 CH2(27), 77.08 CH(6), 113.96 CH2(33), 114.98
ArC(9), 116.60 ArC(22), 122.20 ArC(17,18), 122.68 ArC(21), 124.16 ArC(12),
127.981 ArC(23), 128.20 ArC(15,16), 132.23 ArC(13), 132.26 ArC(14) 136.77
ArC(10),139.00 ArC(11), 142.63 CH(32), 151.07 ArC(19), 151.14 ArC(24), 152.38
=
ArC(26), 153.60 ArC(8), 164.42 C O(20).
4-((R)-2-heptyloxy)-3-nitro-4-biphenyl-4-(9-octenyloxy)-3-fluorobenzoate (13).
Prepared according to modified known procedure [6].
78.9% yield.
1H NMR (CDCl3, TMS) d (ppm): 0.83 (t, 3H, CH3(1), J1 ¼ 6.9, J2 ¼ 6.9),
1.19–2.28 (m, 12H, CH2(2,3,4,29,30,31)), 1.31 (d, 3H, CH3(7), J ¼ 6.1), 1.43 (m,
2H, CH2(5)), 1.51 (m, 2H, CH2(28)), 2.01 (m, 2H, CH2(32)), 4.05 (t, 2H,
=
CH2O(27), J1 ¼ 6.5, J2 ¼ 6.5), 4.48 (m, 1H, CH(6)), 4.88 (d, 1H, CH CH2(34),
=
=
J ¼ 10.2), 4.94 (d, 1H, CH CH2(35), J ¼ 17.1), 5.75 (m, 1H, CH CH2(33)), 6.97
(t, 1H, ArH(25), J1 ¼ 8.3, J2 ¼ 8.4), 7.07 (d, 1H, ArH(9), J ¼ 8.8), 7. 21 (d, 2H,
ArH(17,18), J ¼ 8.7), 7.51 (d, 2H, ArH(15,16), J ¼ 8.6), 7.62 (dd, ArH(11), J1 ¼ 2.3,
J2 ¼ 8.7), 7.84 (dd, 1H, ArH(23), J1 ¼ 1.9, J2 ¼ 11.5), 7.90 (d, 1H, ArH(22), 8.7),
7.95 (d, 1H, ArH(12), J ¼ 2.3).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 14.38 CH3(1), 19.97 CH3(7), 22.95
CH2(2), 25.36 CH2(4), 26.13 CH2(29), 29.16 CH2(28,31), 29.35 CH2(30), 30.10
CH2(3), 32.09 CH2(32), 34.06 CH2(5), 69.83 CH2(27), 77.02 CH(6), 114.78
CH2 ¼ CH(34), 116.57 ArC(9,23), 118.13 ArC(25), 122.70 ArC(17,18), 124.16
ArC(21), 128.20 ArC(12), 129.97 ArC(22), 129.97 ArC(13), 132.29 ArC(15,16),
132.91 ArC(14), 136.75 ArC(10,11), 139.30 CH2 ¼ CH(33), 151.05 ArC(19), 151.31
=
ArC(26), 152.41 ArC(8), 152.51 ArC(24), 164.44 C O(20).
4-((R)-2-heptyloxy)-3-nitro-4-biphenyl-4-(9-decenyloxy)-3-fluorobenzoate (14).
Prepared according to modified known procedure [6].
80% yield.
1H NMR (CDCl3, TMS) d (ppm): 0.83 (t, 3H, CH3(1), J1 ¼ 6.9, J2 ¼ 6.9),
1.19–2.28 (m, 16H, CH2(2,3,4,29,30,31,32,33)), 1.31 (d, 3H, CH3(7), J ¼ 6.1), 1.43
(m, 2H, CH2(5)), 1.51 (m, 2H, CH2(28)), 2.01 (m, 2H, CH2(32)), 4.05 (t, 2H,
=
CH2O(27), J1 ¼ 6.5, J2 ¼ 6.5), 4.48 (m, 1H, CH(6)), 4.88 (d, 1H, CH CH2(34),
=
=
J ¼ 10.2), 4.94 (d, 1H, CH CH2(35), J ¼ 17.1), 5.75 (m, 1H, CH CH2(33)), 6.97
(t, 1H, ArH(25), J1 ¼ 8.3, J2 ¼ 8.4), 7.07 (d, 1H, ArH(9), J ¼ 8.8), 7. 21 (d, 2H,
ArH(17,18), J ¼ 8.7), 7.51 (d, 2H, ArH(15,16), J ¼ 8.6), 7.62 (dd, ArH(11), J1 ¼ 2.3,
J2 ¼ 8.7), 7.84 (dd, 1H, ArH(23), J1 ¼ 1.9, J2 ¼ 11.5), 7.90 (d, 1H, ArH(22), 8.7),
7.95 (d, 1H, ArH(12), J ¼ 2.3).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 14.38 CH3(1), 19.97 CH3(7), 22.95
CH2(2), 25.36 CH2(4), 26.13 CH2(29), 29.16 CH2(28,31), 29.35 CH2(30), 29.70
CH2(33), 30.10 CH2(3), 32.09 CH2(32), 33.9 CH2 (34), 34.06 CH2(5), 69.83
CH2(27), 77.02 CH(6), 115.78 CH2 ¼ CH(36), 116.57 ArC(9,23), 118.13 ArC(25),
122.70 ArC(17,18), 124.16 ArC(21), 128.20 ArC(12), 129.97 ArC(22), 129.97
ArC(13), 132.29 ArC(15,16), 132.91 ArC(14), 136.75ArC(10,11), 137.70

Fluorinated Organosiloxane Liquid Crystals
129=[651]
CH2 ¼ CH(35), 151.05 ArC(19), 151.31 ArC(26), 152.41 ArC(8), 152.51 ArC(24),
=
164.44 C O(20).
Bis 1-[30-Nitro-40-(R)-(1-methylhexyloxy) Phenyl] Phenyl-4-(1,1,3,3,5,5-hexa-
methyltrisiloxyhexyloxy)-3-fluorobenzoate (15). Prepared according to modified
known procedure [6].
29.1% yield.
1H NMR (400 MHz, CDCL3, TMS)
d (ppm): 0.02–0.08 (m, 18H,
CH3(33,330,34,340,35,350), 0.67–0.87 (m, 6H, CH3(1,10)), 1.14–1.30 (m, 28H,
CH2(2,20,3,30,4,40,29,290,30,300,31,310,320,320), 1.32 (d, 6H,CH3(7,70), J ¼ 6.0 Hz),
1.55–1.61 (m, 4H, CH2(5,50)), 1.77–1.84 (m, 4H, CH2(28,280)), 4.06 (t, 4H,
CH2(27,270), J1 ¼ 6.6, J2 ¼ 6.8), 4.47 (m, 2H, CH(6,60)),6.97 (t, 2H, ArH(25,250),
J1 ¼ 8.4 Hz, J2 ¼ 8.3 Hz), 7.62 (dd, 2H, ArH(11,110), J1 ¼ 2.4 Hz, J2 ¼ 8.4 Hz), 7.21
(d, 4H, ArH(17,170,18,180), J ¼ 8.6 Hz), 7.51 (d, 4H, ArH(15,150,16,160), J ¼ 8.6 Hz),
7.83 (dd, 2H, ArH(22,220) J1 ¼ 2.0 Hz, J2 ¼ 11.5 Hz), 7.62 (dd, 2H, ArH(11,110),
J1 ¼ 2.4 Hz, J2 ¼ 8.4 Hz), 7.90 (d, 2H, ArH(23,230), J ¼ 8.5 Hz), 7.92 (d, 2H,
ArH(12,120), J ¼ 2.3 Hz).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 1.37 CH3(33,330,34,340), 1.42
CH3(35,350), 14.49 CH3(1,10), 19.14 CH2(32,320), 19.95 CH2(31,310), 22.94
CH2(7,70), 23.04 CH3(4,40), 23.08 CH2(2,20), 25.35 CH2(29,290), 29.37 CH2(28,280),
31.98 CH2(3,30), 32.32 CH2(30,300), 36.61 CH2(5,50), 69.90 CH2(27,270), 77.02
CH(6,60),
113.88
ArCH(19,190,22,220),
116.56
ArCH(25,250),
122.70
ArCH(17,170,18,180), 123.84 ArCH(12,120), 124.17 C(21,210), 127.82 ArCH(23,230),
128.20 ArCH(15,150,16,160), 132.28 ArC(13,130), 132.93 ArC(14,140), 136.76
ArC(10,100,11,1100), 151.06 ArC(19,1900), 151.30 ArC(26,260), 151.43 ArC(24,240),
=
153.58 ArCH(8,8 ), 164.42 C O(20,20 ).
Bis 1-[30-Nitro-40-(R)-(1-methylhexyloxy) Phenyl] Phenyl-4-(1,1,3,3,5,5-Hexa-
methyltrisiloxyheptyloxy)-3-fluorobenzoate (16). Prepared according to modified
known procedure [6].
40.1% yield.
1H NMR (400 MHz, CDCL3, TMS)
d (ppm): 0.02–0.08 (m, 18H,
CH3(34,340,35,350,36,360), 0.79–0.84 (m, 6H, CH3(1,10)), 1.15–1.27 (m, 16H, CH2(2,
20,3,30,4,40,29,290,30,300,31,310,32,320,33,330)), 1.32 (d, 6H,CH3(7,70), J ¼ 6.1),
1.56–1.62 (m, 4H, CH2(5,50)), 1.72–1.82 (m, 4H, CH2(28,280)), 4.06 (t, 4H,
CH2(27,270), J1 ¼ 6.5, J2 ¼ 6.5), 4.48 (m, 2H, CH(6,60)), 6.97 (t, 2H, ArH(25,250),
J1 ¼ 8.3 Hz, J2 ¼ 8.3 Hz), 7.06 (d, 2H, ArH(9,90), J ¼ 8.9 Hz), 7.22 (d, 4H,
ArH(17,170,18,180), J ¼ 8.5), 7.52 (d, 4H, ArH(15,150,16,160), J ¼ 8.5), 7.63 (dd, 2H,
ArH(22,220) J1 ¼ 2.2 Hz, J2 ¼ 8.7 Hz), 7.83 (d, 2H, ArH(11,110), J ¼ 11.5), 7.91 (m,
2H, ArH(23,230)), 7.92 (d, 2H, ArH(12,120), J ¼ 2.2).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 0.69 CH3(34,340,35,350), 1.42
CH3(36,360), 14.35 CH3(1,10), 14.47 CH2(33,330), 19.96 CH2(32,320), 22.93
CH2(7,70), 22.97 CH3(2,20), 25.34 CH2(4,40), 26.23 CH2(29,290), 29.41 CH2(30,300),
30.09 CH2(28,280), 32.08 CH2(3,30), 32.11 CH2(31,310), 36.62 CH2(5,50), 69.93
CH2(27,270), 113.96 ArC(22,220), 116.60 ArC(9,90), 118.33 ArC(25,250), 122.69
ArC(17,170,18,180), 124.15 ArC(21,210), 127.82 C(23,230), 128.18 ArC(15,150,16,160),
132.25 ArC(13,130), 132.95 ArC(14,140), 136.77 ArC(10,100), 141.63 ArCH(11,110),
151.08 ArC(19,1900), 151.30 ArC(24,240), 152.54 ArC(26,260), 153.60 ArCH(8,80),
=
164.43 C O(20,20 ).

130=[652]
W. M. Zoghaib et al.
Bis 1-[30-Nitro-40-(R)-(1-methylhexyloxy) Phenyl] Phenyl-4-(1,1,3,3,5,5-hexa-
methyltrisiloxyoctyloxy)-3-fluorobenzoate (17). Prepared according to modified
known procedure [6].
57.4% yield.
1H NMR (400 MHz, CDCL3, TMS)
d (ppm): 0.004–0.08 (m, 18H,
CH3(35,350,36,360,37,370), 0.85 (t, 6H, CH3(1,10)0 J1 ¼ 7.3 Hz, J2 ¼ 5.7 Hz), 1.17–1.26
(m, 18H, CH2(2,20,3,30,4,40,29,290,30,300,31,310,32,320)), 1.32 (d, 6H,CH3(7,70),
J ¼ 6.1 Hz), 1.36–1.46 (m, 8H, CH2(33,330,34,340,), 1.59–1.61 (m, 4H, CH2(5,50)),
1.77–1.82 (m, 4H, CH2(28,280)), 4.06 (t, 4H, CH2(27,270), J1 ¼ 6.5, J2 ¼ 6.6), 4.48
(m, 2H, CH(6,60)), 6.97 (t, 2H, ArH(25,250), J1 ¼ 8.3 Hz, J2 ¼ 8.3 Hz), 7.06 (d, 2H,
ArH(9,90), J ¼ 8.9 Hz), 7.21 (t, 4H, ArH(17,170,18,180), J1 ¼ 8.6 Hz, J2 ¼ 6.7 Hz),
7.52 (d, 4H, ArH(15,150,16,160), J ¼ 8.6 Hz), 7.63 (dd, 2H, ArH(22,220) J1 ¼ 2.3 Hz,
J2 ¼ 8.7 Hz), 7.83 (dd, 2H, ArH(11,110), J1 ¼ 2.0 Hz, J2 ¼ 11.5 Hz), 7.91 (d, 2H,
ArH(23,230), J ¼ 8.8 Hz), 7.93 (d, 2H, ArH(12,120), J ¼ 2.3 Hz).
13C NMR (100 MHz, CDCL3, TMS) d (ppm): 0.69 CH3(35,350,36,360), 1.25
CH3(37,370), 14.37 CH3(1,10), 14.47 CH2(34,340), 19.97 CH2(33,330), 22.94
CH2(4,40), 23.03 CH3(7,70), 25.35 CH2(2,20), 26.27 CH2(29,290), 29.40 CH2(31,310),
29.58 CH2(28,280), 29.68 CH2(30,300), 32.09 CH2(3,30), 32.18 CH2(32,320), 36.61
CH2(5,50), 69.91 CH2(27,270), 77.03 CH(6,60), 113.90 ArCH(22,220), 116.56
ArCH(9,90), 118.13 ArCH(25,250), 122.70 ArCH(17,170,18,180), 124.18
ArCH(12,120), 127.80 C(21,210), 127.83 ArCH(23,230), 128.21 ArCH(15,150,16,160),
132.29 ArC(13,130), 132.93 ArC(14,140), 136.77 ArC(10,100), 141.58 ArCH(11,110),
151.05 ArC(19,1900), 151.11 ArC(26,260), 151.30 ArC(24,240), 152.43 ArCH(8,80),
=
164.46 C O(20,20 ).
Bis 1-[30-Nitro-40-(R)-(1-methylhexyloxy) Phenyl] Phenyl-4-(1,1,3,3,5,5-hexa-
methyltrisiloxydecyloxy)-3-fluorobenzoate (18). Prepared according to modified
known procedure [6].
75% yield.
1H NMR (CDCl3, TMS) d (ppm) 0.95 (t, 3H, CH2CH3); 1.33 (m, 2H, CH3CH2);
1.29 (m, 4H, CH2CH2); 1.66 (m, 2H, CHCH2); 3.86 (m, 1H, OCH); 1.43 (d, 3H,
Table 1. The observed transition temperatures between stable phases
No. of carbon
Heating
Cooling
81
68
6
7
8
10
K ꢁ! 1
K ꢁ 1
86
K ꢁ! 1
77
66
K ꢁ 1
64
K ꢁ! 1
K ꢁ 1
64
64
SmCꢀ ! 1
SmCꢀ ! 1
Table 2. Transition from the quenched metastable
smectic to isotropic
No. of carbon
Heating
41
SmCꢀ ꢁ! 1
52
7
8
SmCꢀ ꢁ! 1

Fluorinated Organosiloxane Liquid Crystals
131=[653]
CHCH3); 7.08 (dd, 1H, ArH): 7.76 (dd, 1H, ArH): 8.30 (s, 1H, ArH);7.31 (dd, 2H,
ArH); 6.79 (dd, 2H, ArH); 1.18–2.1 (m, 14H, (CH2)), 3.58 (t, 2H, CH2O), 6.92 to
7.88 (m, 8H, Ar-H); 0.9–1.5 (m, 18H, SiCH3).
4. Polarised Ligt Microscopy Observations
The preliminary characterization of the first materials in the series was performed
using polarized light microscopy. The transition temperatures observed are
summarized in Table 1.
The material with 6 carbon atoms in the alkyl chain does not display any meso-
phases. On slow cooling the materials with 7 and 8 carbon atoms from the isotropic
phase crystallization is observed; on rapid cooling a metastable smectic phase is
observed. The response of this metastable smectic phase to an electric field is that
of a ferroelectric SmCꢀ phase. After a few minutes, the crystalline phase grows from
the smectic phase. The transition temperatures from the metastable smectic to
isotropic phase are given in Table 2.
The material with 10 carbon atoms in the chain displays a stable smectic phase at
room temperature. The preliminary observations of the electro-optic response would
indicate that the smectic phase is a de-Vries type SmAꢀ however more work is
required to confirm the nature of the observed phase.
5. Conclusion
It would appear that linking two mesogenic moieties tothe siloxane reduces the ability to
form a smectic phase and increases the tendency to crystallize. The mono-mesogen with
6 carbon atoms in the chain reported in reference [4] displays a stable smectic de-Vries
phase at room temperature. The homologue with 11 carbon atom in the chains is cur-
rently under preparation. A complete characterization of all the materials in the series
after thorough verification of the purity will be given in a forthcoming publication.
Acknowledgment
This work is supported by Sultan Qaboos University Internal Grant number: IG=SI=
Phys=09=03.
References
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Rev E, 67, 051709.
[4] Naciri, J., Carboni, C., & George, A. K. (2003). Liq. Cryst., 30, 219.
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[6] Naciri, J., Ruth, J., Crawford, G., Shashindar, R., & Ratna, B. R. (1995). Chem. Mater, 7,
1397.
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