Zwitterionic pyridinium derivatives of [closo-1-CB9H10]−and [closo-1-CB11H12]−as high Δεadditives to a nematic host

Pecyna, Jacek; Pociecha, Damian; Kaszyński, Piotr

doi:10.1039/c3tc32351j

Cited by 33 publications

(32 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…63 Among a number of important topics not specifically covered are nonlinear optical materials, [166][167][168][169][170][171][172] liquid crystals, [173][174][175][176][177][178][179] and ionic liquids, 180 among others. I have barely scratched the surface of the burgeoning field of biomedical applications, on which a formidable literature has accumulated.…”

Section: Resultsmentioning

confidence: 99%

Carboranes in the chemist's toolbox

2015

View full text Add to dashboard Cite

Once seldom encountered outside of a few laboratories, carboranes are now everywhere, playing a role in the development of a broad range of technologies encompassing organic synthesis, radionuclide handling, drug design, heat-resistant polymers, cancer therapy, nanomaterials, catalysis, metal-organic frameworks, molecular machines, batteries, electronic devices, and more. This perspective highlights selected examples in which the special attributes of carboranes and metallacarboranes are being exploited for targeted purposes in the laboratory and in the wider world.

show abstract

Section: Resultsmentioning

confidence: 99%

Carboranes in the chemist's toolbox

2015

View full text Add to dashboard Cite

show abstract

“…5 During recrystallization of 3b from EtOH/H 2 O, partial exchange of the methyl group for ethyl was observed. This suggests that the C(1) 4-methoxypyridinium derivative is also susceptible to demethy- lation and may provide means to more efficient preparation of higher C(1) 4-alkoxypyridinium homologues.…”

Section: ■ Introductionmentioning

confidence: 98%

“…2 In this context, we initially investigated 1-sulfonium derivatives of type IA, 3,4 and later we developed a convenient method for access to 1-pyridinium zwitterions of anions A and B. 5 Although materials of type IA and IB are effective additives that increase dielectric anisotropy Δε of a nematic liquid crystal host, these polar materials rarely exhibit liquid crystalline properties themselves, have high melting points, and display limited solubility in nematic hosts.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, extension of the pentyl chain in 13 to decyl results in induction of an SmA phase with the isotropic transition at 200°C. 5 The difference in thermal behavior of the two isomers is related to the stability of the crystalline phase governed by the magnitude of the molecular dipole moment: μ = 12.2 D for 1c and μ = 18.2 D for 13, according to B3LYP/6-31G(d,p) calculations in vacuum.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis and Characterization of 12-Pyridinium Derivatives of the [closo-1-CB₁₁H₁₂]⁻ Anion

et al. 2014

Self Cite

View full text Add to dashboard Cite

Diazotization of [closo-1-CB11H10-1-R-12-NH2](-)[NMe4](+) (4[NMe4]) in neat 4-methoxypyridine leads to 12-(4-methoxypyridinium) zwitterions [closo-1-CB11H10-1-R-12-(4-MeOC5H4N)] (2) in ∼50% yield. Demethylation of 2 with LiCl in dimethylformamide provides access to 12-pyridones 5[NMe4], which can be O-alkylated with alkyl triflates giving 12-(4-alkoxypyridinium) zwitterions, such as 1. This three-step process is more efficient than direct diazotization of amine 4[NMe4] in neat higher 4-alkoxypyridine. The new method was demonstrated for the synthesis of [closo-1-CB11H10-1-C5H11-12-(4-C7H15OC5H4N)] (1c), which exhibits a smectic A phase. Molecular and electronic structures of 4-methoxypyridinium zwitterion 2b and its C(1) isomer [closo-1-CB11H11-1-(4-MeOC5H4N)] (3b) were investigated by single-crystal X-ray diffraction and spectroscopic methods, respectively, and the experimental results were compared to those obtained with density functional theory methods. Lastly, the mechanism for formation of zwitterions 2 was investigated computationally revealing low energy for dediazoniation of the [closo-1-CB11H10-1-R-12-N2] (14) intermediate (ΔG298 ≈ 25 kcal/mol) to form boronium ylide 15, with weak dependence on substituent R. Dinitrogen derivative 14c was observed by (11)B NMR spectroscopy.

show abstract

“…In diketonate and BODIPY derivatives such as 1 or subphthalocyanines, the boron atom is surrounded by af latm esogenic p-system, which not only contributes to the liquid crystalline self-assembly,b ut also adds favorable absorption and emission characteristics. In contrast, the bulky closo-carboranes 2 are incorporated into rigid rod-likeu nits to obtain suitable mesomorphicp roperties.T hese boron clusters are not only suitable for liquid crystal display applicationsd ue to their high dielectric anisotropy De, [31,36,37] but also as battery electrolytes. [38] Moreover,t hey provided insight into fundamental aspects of soft matter such as the contribution of Coulomb and dipolar interactions on the stabilization of mesophases.…”

mentioning

confidence: 99%

Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self‐Assembly

Wöhrle

Gündemir

Frey

et al. 2017

Chemistry A European J

View full text Add to dashboard Cite

A series of MIDA (N-methylimino diacetic acid) boronates carrying 4-alkoxy, 3,4-bisalkoxy, or 3,4,5-trisalkoxyphenyl substituents were synthesized and their mesomorphic properties characterized by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) techniques such as small- and wide-angle X-ray scattering (SAXS and WAXS, respectively). Most derivatives were liquid crystalline. In the case of mono- and bisalkoxy-substituted derivatives, C chains already induced smectic A (SmA) mesophases despite the bulky MIDA head group. With increasing chain length, columnar hexagonal (Col ) phases replaced SmA phases in the disubstituted series. Quantum chemical calculations on a series of MIDA boronates show that the B-N bond is a dative bond with a positive charge on the boron atom and negative charges on the nitrogen and oxygen atoms. In addition, no π-interaction between the aryl moiety and B-N bond was found, thus the mesogenic unit is electronically decoupled from the MIDA head group. These theoretical findings were supported by IR and Raman spectra as well as by asingle crystal structure analysis of 4-ethoxyphenyl MIDA boronate. Calculations of the electrostatic potential of the MIDA boronate reveal a special polarity pattern that can support the formation of a two-dimensional network and is likely to explain the liquid crystalline self-assembly. The absence of any electronic cross-talk between the MIDA head group and B-aryl or B-alkyl substituents allows the efficient tailoring of the mesophase type through variation of the substituents.

show abstract

Zwitterionic pyridinium derivatives of [closo-1-CB₉H₁₀]⁻and [closo-1-CB₁₁H₁₂]⁻as high Δεadditives to a nematic host

Abstract: Pyridinium zwitterions ofcloso-boranes were conveniently obtained from 4-alkoxypyrylium salts and investigated as high Δεadditives to nematics.

Cited by 33 publications

References 22 publications

Carboranes in the chemist's toolbox

Carboranes in the chemist's toolbox

Synthesis and Characterization of 12-Pyridinium Derivatives of the [closo-1-CB₁₁H₁₂]⁻ Anion

Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self‐Assembly

Contact Info

Product

Resources

About

Zwitterionic pyridinium derivatives of [closo-1-CB9H10]−and [closo-1-CB11H12]−as high Δεadditives to a nematic host

Abstract: Pyridinium zwitterions ofcloso-boranes were conveniently obtained from 4-alkoxypyrylium salts and investigated as high Δεadditives to nematics.

Cited by 33 publications

References 22 publications

Carboranes in the chemist's toolbox

Carboranes in the chemist's toolbox

Synthesis and Characterization of 12-Pyridinium Derivatives of the [closo-1-CB11H12]− Anion

Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self‐Assembly

Contact Info

Product

Resources

About

Zwitterionic pyridinium derivatives of [closo-1-CB₉H₁₀]⁻and [closo-1-CB₁₁H₁₂]⁻as high Δεadditives to a nematic host

Synthesis and Characterization of 12-Pyridinium Derivatives of the [closo-1-CB₁₁H₁₂]⁻ Anion