Processes in Cellulose Derivative Structures

Onofrei, Mihaela Dorina; Dobos, Adina Maria; Ioan, Silvia

doi:10.1002/9781118872246.ch14

Cited by 6 publications

(10 citation statements)

References 120 publications

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“…Broad monosignate CD bands due to n -π * transition from alkyl esters of CABu and CTA thin films appeared at ~215 nm with (+)-sign and ~205 nm with (–)-sign, respectively (Guo et al, 2018 ). These (+)-and (–)-sign CD bands at 205 and 215 nm in the solid film reflect from left-handed helicity of CABu and right-handed helicity of CTA in solutions, respectively (Dubois et al, 1998 ; Onofrei et al, 2015 ), though CABu and CTA are β-(1 → 4) linked polymers made of D -glucose framework as a common repeating unit.…”

Section: Resultsmentioning

confidence: 99%

Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII Tris(β-diketonate) Upon Intermolecular Chirality Transfer From Poly- and Monosaccharide Alkyl Esters and α-Pinene: Emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)

et al. 2020

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Section: Resultsmentioning

confidence: 99%

Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII Tris(β-diketonate) Upon Intermolecular Chirality Transfer From Poly- and Monosaccharide Alkyl Esters and α-Pinene: Emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)

et al. 2020

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“…For comparison, with respect to the ground-state chirality in the CABu film, the UV–vis and CD spectra at the S 0 → S 1 transitions of Trimer, Heptamer, and PF6 and, for comparison, those of Monomer, Dimer, Pentamer, and PF8 are shown in Figure a and Figure S2a, respectively. Similarly, the right -hand helicity , and/or d -glucose chirality of CABu efficiently transferred to these fluorenes. The bisignate CD profiles associated with the (+)- and (−)-signs at the first and second Cotton bands in CABu are quite similar to those in the CTA films, except for those of Monomer, PF6, and PF8 for unknown reasons.…”

Section: Results and Discussionmentioning

confidence: 96%

“…These induced CD signals from all of the fluorene derivatives clearly demonstrate that the efficient induction of d -β-glucose chirality and/or its main chain helicity is possible in a family of achiral (or CD-silent) fluorene derivatives via intermolecular interactions. Given that CTA, which possesses five chiral centers per pyranose ring, prefers left -handed helicity in dilute CHCl 3 , − we assumed that the three acetate groups per pyranose attached to these chiral centers provided the fluorenes with chirality/helicity transfer capability. Although the acetate groups have no chirality individually, their restricted rotational freedom along the C–O–C and C–C–O–C bonds (Chart , shown as red bold lines for CTA) is expected lead to the twisted geometry of the fluorene main chain in a preferred screw sense, as proven by the bisignate CD spectra. , …”

Section: Results and Discussionmentioning

confidence: 99%

“…These celluloses are readily soluble in chloroform and nonchromophoric chiral polymers. Although CTA and CABu share d -glucose repeat units with a β(1→4) linkage, they prefer left- and right -helix senses, respectively. − As chromophoric and luminophoric probes, we highlighted CD-silent/CPL-silent 9,9-dialkylfluorene oligomers and polymers (Chart ) because dialkylfluorenes are well-established semiflexible π-conjugated molecules that can enable us to systematically investigate the molecular weight dependency of their (chir)optical properties in the ground and photoexcited states. − …”

Section: Introductionmentioning

confidence: 99%

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Oligo- and Polyfluorenes Meet Cellulose Alkyl Esters: Retention, Inversion, and Racemization of Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD) via Intermolecular C–H/O═C Interactions

2017

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Detecting chiral/helical interactions among noncharged molecules and polymers is difficult due to their unlimited intra- and intermolecular rotational freedom. To clarify the chirality and/or helicity transfer from a chiral polymer to noncharged achiral molecules, we chose stiff cellulose triacetate (CTA) and cellulose acetate butyrate (CABu) as nonchromophoric helical/chiral polymers. Here, we highlighted stiff 9,9-dialkylfluorene oligomers and polymers (repeating number n = 1, 2, 3, 5, 7, 47, 201) as achiral chromophoric luminophores. These fluorenes revealed clear circularly polarized luminescence (CPL) and bisignate circular dichroism (CD) signals when embedded into CTA and CABu films. In the ground state, when n = 1–7, CTA and CABu commonly induced (+)-CD signals, whereas when n ≥ 47, they induced (+)- and (−)-CD signs, respectively. In the photoexcited state, when n ≥ 3, CTA and CABu induced (+)- and (−)-CPL signs, respectively. Upon comparing the ground and photoexcited states, when n = 2–7, CABu induced (+)-CD and (−)-CPL signs, whereas when n ≥ 3, CTA induced the same (+)-CD and (+)-CPL signs. A conflict between the d-glucose chirality and main-chain helicity was assumed to be responsible for these anomalies because CTA and CABu, despite being common frameworks of β(1→4)-linked d-glucose residues, prefer left- and right-handed helicities, respectively. Molecular mechanics/molecular dynamics simulations suggested intermolecular C–H/OC interactions between H–C (due to the methylene group of the dioctylfluorenes) and OC (due to the acetyl group attached to the d-glucose of CTA). This simulation was confirmed by the first detection of a clear cross-peak at 13CO (δC = 170.6 ppm, CTA) and the finding CH2 protons (δH = 2.55 ppm, fluorene with n = 201) represented the shortest C–1H/O13C distance according to the phase-modulated Lee–Goldburg homonuclear decoupling of solid-state 1H–13C HETCOR NMR spectroscopy. Moreover, the first photoinduced change in the real-time CPL/PL amplitude measurement of optically active fluorenes in CTA revealed that the stability of the chiroptical state increases as n increases and remains unchanged when n ≥ 47.

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“…On the Chart 1. Chemical Structures of Cellulose Triphenylcarbamate (CTPC), 9,9-Di-n-hexylfluorene Trimer (F3), 9,9-Di-nhexylfluorene Pentamer (F5), 9,9-Di-n-hexylfluorene heptamer (F7), Poly(9,9-di-n-hexylfluorene) (PF6), Poly(9,9-di-noctylfluorene) (PF8), Poly(9,9-di-n-octylfluorene-alt-ethynylene) (PF8E), Poly(9,9-di-n-octylfluorene-alt-bithiophene) (PF8T2), and Poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (PF8BT) a other hand, CTA and CABu film casting from their CHCl 3 solutions showed (−)-and (+)-sign CD spectral profiles (Figure S3a) arising from the CTA prevailing right-hand helix and CABu prevailing left-hand helix in solutions, 19,20 respectively. CTPC is a single polymer chirality platform but has bistability of helix sense in lyotropic liquid crystalline phase.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Ambidextrous Chirality Transfer Capability from Cellulose Tris(phenylcarbamate) to Nonhelical Chainlike Luminophores: Achiral Solvent-Driven Helix-Helix Transition of Oligo- and Polyfluorenes Revealed by Sign Inversion of Circularly Polarized Luminescence and Circular Dichroism Spectra

et al. 2018

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We investigated whether helicity and/or chirality of cellulose tris(phenylcarbamate) (CTPC) can transfer to noncharged, nonhelical oligo- and polyfluorenes when CTPC was employed as a solution processable homochiral platform of a D-glucose-skeletal polymer. Noticeably, CTPC revealed the solvent-driven, ambidextrous intermolecular helicity/chirality transfer capability to these fluorenes. The chiroptical inversion characteristics of circularly polarized luminescence (CPL) and the corresponding CD spectra were realized by solely choosing a proper achiral solvent and/or achiral cosolvent. When the solution of PF6 and CTPC in tetrahydrofuran (THF) was cast on a quartz substrate, the dissymmetry ratio of CPL (g) from the polymer film showed g = +2.1 × 10 at 429 nm. Conversely, when dichloromethane (DCM) was used as the solvent, the CPL sign was inverted to g = -2.4 × 10 at 429 nm. The dissymmetry ratio of Cotton CD band (g) from the THF solution was g = +3.2 × 10 at 392 nm; conversely, from the DCM, the CD sign inverted to g = -0.8 × 10 at 371 nm. The sign and magnitude of the g values were interpreted to a London dispersion term (δ) of Hansen solubility parameter (δ) of the casting solvents rather than a dipole-dipole interaction term (δ) and a hydrogen bonding interaction term (δ) of the δ values and dielectric constant (ε). Analysis of solvent-driven changes in FTIR spectra, wide-angle X-ray diffraction profiles, and differential scanning calorimetry diagrams indicated that solvent driven on-off switching of multiple hydrogen bonds due to three urethane groups of CTPC play the key for the inversion. Intermolecular CH/π and π-π interactions among phenyl rings and alkyl groups were assumed to be crucial for helicity/chirality transfer capability based on molecular mechanics and molecular dynamics simulations of PF6-CTPC hybrids. These chiroptical inversion characteristics arose from solvent-driven order-disorder transition characteristics of the CTPC helix rather than a helix-helix transition of CTPC itself.

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Processes in Cellulose Derivative Structures

Cited by 6 publications

References 120 publications

Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII Tris(β-diketonate) Upon Intermolecular Chirality Transfer From Poly- and Monosaccharide Alkyl Esters and α-Pinene: Emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)

Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII Tris(β-diketonate) Upon Intermolecular Chirality Transfer From Poly- and Monosaccharide Alkyl Esters and α-Pinene: Emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)

Oligo- and Polyfluorenes Meet Cellulose Alkyl Esters: Retention, Inversion, and Racemization of Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD) via Intermolecular C–H/O═C Interactions

Ambidextrous Chirality Transfer Capability from Cellulose Tris(phenylcarbamate) to Nonhelical Chainlike Luminophores: Achiral Solvent-Driven Helix-Helix Transition of Oligo- and Polyfluorenes Revealed by Sign Inversion of Circularly Polarized Luminescence and Circular Dichroism Spectra

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