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A series of axially chiral 5,5'- and 6,6'-dialkanoyloxy-2,2'-spirobiindan-1,1'-dione dopants, (R)-2 and (R)-4a-4c were synthesized in optically pure form and their ferroelectric polarization powers, δp, measured in four liquid crystal hosts with isotropic (I)-nematic (N)-smectic A (SmA)-smectic C (SmC) phase sequences. The results show that the sign of polarization P S induced by (R)-2 and (R)-4a-4c follows the same trend as that previously reported for the 5,5'- and 6,6'-diheptyloxy-2,2'-spirobiindan-1,1'-dione dopants, (R)-1 and (R)-3. The polarization induced by (R)-2 in the host DFT is below detection limits, and the sign of P S was found to invert as a function of temperature at mole fractions as low as 0.01. On the other hand, the polarization power of the 6,6'-diheptanoyloxy dopant (R)-4b in the host NCB76 is -1449 nC cm-2, the fourth highest value reported so far, and more than three times the δp value of the 5,5'-diheptanoyloxy analogue (R)-2 in that host (+474 nC cm-2). Results of 2H NMR experiments suggest that (R)-4b exerts stronger local perturbations in NCB76 than (R)-2, and that these perturbations may be chiral in nature. [ABSTRACT FROM AUTHOR]

The polarization powers δp of four chiral dopants with (R,R)-2,3-difluorooctyloxy side-chains were measured in four liquid crystal hosts with isotropic (I)-nematic (N)-smectic A (SmA)-smectic C (SmC) phase sequences. The four chiral dopants differ in terms of their core structures: 2-phenylpyridine (MDW950), biphenyl (5), 2-phenylpyrimidine (6) and 2-(3-nitrophenyl)pyrimidine (7). In each case, δp varies with the structure of the liquid crystal host, which is consistent with the behaviour of so-called Type II dopants that normally feature a chiral core structure. The δp(host) profile was found to depend on the degree of biaxiality of the dopant core structure, and on the degree of steric coupling between the chiral 2,3-difluorooctyloxy side-chain and the core. Conformational analyses at the B3LYP/6-31G* level suggest that the 2,3-difluorooctyloxy side-chain is conformationally more rigid than conventional chiral side-chains due to the added electrostatic repulsion of the two adjacent fluoro groups combined with the hyperconjugative 'gauche effect', and may therefore have a higher degree of biaxiality on the time average. This biaxial character should make the chiral side-chain more sensitive to variations in quadrupolar ordering imposed by the SmC phase of the liquid crystal host, and may therefore explain the dependence of δp on the host structure reported herein. [ABSTRACT FROM AUTHOR]

The chiral fluorenone mesogens ( R )‐1‐fluoro‐2‐(2‐octyloxy)‐7‐(4‐undecyloxybenzoyloxy)fluoren‐9‐one (2) and ( R )‐2‐(2‐octyloxy)‐7‐(4‐undecyloxybenzoyloxy)‐3‐azafluoren‐9‐one (3) were synthesized using a combined ortho ‐directed and remote metalation strategy, which also incorporates a Suzuki–Miyaura crosscoupling step. These compounds form chiral SmC* liquid crystal phases with reduced polarizations (P o ) of +475 and +332 nC cm -2 at 10 K below the Curie point, respectively. These values are considerably larger than that previously reported for the unsubstituted fluorenone ( R )‐2‐(2‐octyloxy)‐7‐(4‐undecyloxybenzoyloxy)fluoren‐9‐one (1), which is +111 nC cm -2 at 10 K below the Curie point. Molecular modelling based on the Boulder model suggests that the larger polarizations result from a conformational bias of the fluorenone core dipole moment along the polar axis of the SmC* phase caused by stereo‐polar coupling with the chiral 2‐octyloxy side chain. [ABSTRACT FROM AUTHOR]

Two new ferroelectric liquid crystals, 4-[(S)-1-(ethoxycarbonyl)]ethyl 4-[4-(9-decenyloxy)biphenyl]azobenzoate (10) and its ester analogue 4-[(S)-1-(ethoxycarbonyl)]ethyl {[4-(9-decenyloxy)]biphenyl-4'-yl}carbonyloxybenzoate (17), and side chain polysiloxane copolymers and terpolymers containing various amounts of 10 and 17 as mesogenic side groups have been synthesized. Their mesomorphic and physical properties have been characterized. Both 10 and 17 exhibit isotropic, SmA*, SmC*, and Sm(I or F)* phases. The copolymer with 17 as the mesogenic group and terpolymers having low content of the azo compound 10 show a SmC* phase over a large temperature range down to room temperature. The copolymer with the azo compound 10 as the mesogenic group is amorphous. [ABSTRACT FROM AUTHOR]

Studies the photoinduced polarization inversion in a ferroelectric liquid crystal (FLC) using an ambidextrous chiral thioindigo dopant. Alkylation of the known compound (R)-6'-hydroxy-5-nitro-6-(2-octyloxy)thioindigo with (R,R)-2,3-difluorooct-1-y1 tosylate; Measurement of the spontaneous polarization of the FLC film.

Studies a photochemically bistable ferroelectric liquid crystal (FLC) photoswitch triggered by a dithienythelene dopant. Reversible photocyclization reaction between colorless ring-opened and colored ring-closed forms; Modulation of the electric polarization for the FLC mixture; Spontaneous polarization before and after irradiation.

The article discusses the formation of ferroelectric liquid crystals (FLCs) with de Vries-like structure. It mentions that FLCs are usually made from achiral liquid crystal mixture and a chiral dopant. It describes the formation of de Vries-like materials which are a class of liquid crystals with layer contractions of less than or equal to one percent. An experiment to create ferroelectric liquid crystals (FLCs) with de Vries-like structure is described.