Transition temperature engineering of octaalkoxycarbonyl phthalocyanines

Sergeyev, Sergey; Debever, Olivier; Pouzet, Eric; Geerts, Yves

doi:10.1039/b704344a

Cited by 23 publications

(14 citation statements)

References 26 publications

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“…The observed mesophases exhibited relatively high thermal stability above 300 °C, though thermal decomposition gradually took place. Moreover, the introduction of branched alkyl chains at the periphery led to a lowering of the melting temperature 43a,e. However, in all cases, no clearing points were observed before the thermal decomposition.…”

Section: Resultsmentioning

confidence: 89%

“…Next, tetrakis‐DBA 8 b and (AE) 6 ‐DBA 9 e with branched alkyl chains were investigated, because it is known that the branched alkyl chains lower the isotropic temperature and increase the domain size 43a,e. TGA measurements on 8 b and 9 e showed gradual thermal decomposition above 150 °C (Figures S12 and S13), similar to what was seen for 9 d ; thus, the isotropization temperatures could not be determined.…”

Section: Resultsmentioning

confidence: 98%

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Syntheses and Properties of Graphyne Fragments: Trigonally Expanded Dehydrobenzo[12]annulenes

Tahara

Yamamoto

Gross

et al. 2013

Chemistry A European J

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We present herein the synthesis and properties of the largest hitherto unknown graphyne fragment, namely trigonally expanded tetrakis(dehydrobenzo[12]annulene)s (tetrakis-DBAs). Intramolecular three-fold alkyne metathesis reactions of hexakis(arylethynyl)DBAs 9 a and 9 b using Fürstner's Mo catalyst furnished tetrakis-DBAs 8 a and 8 b substituted with tert-butyl or branched alkyl ester groups in moderate and fair yields, respectively, demonstrating that the metathesis reaction of this protocol is a powerful tool for the construction of graphyne fragment backbones. For comparison, hexakis(arylethynyl)DBAs 9 c-g have also been prepared. The one-photon absorption spectrum of tetrakis-DBA 8 a bearing tert-butyl groups revealed a remarkable bathochromic shift of the absorption cut-off (λcutoff ) compared with those of previously reported graphyne fragments due to extended π-conjugation. Moreover, in the two-photon absorption spectrum, 8 a showed a large cross-section for a pure hydrocarbon because of the planar para-phenylene-ethynylene conjugation pathways. Hexakis(arylethynyl)-DBAs 9 c-e and 9 g and tetrakis-DBA 8 b bearing electron-withdrawing groups aggregated in chloroform solutions. Comparison between the free energies of 9 e and 8 b bearing the same substituents revealed the more favorable association of the latter due to stronger π-π interactions between the extended π-cores. Polarized optical microscopy observations, DSC, and XRD measurements showed that 8 b and 9 e with branched alkyl ester groups displayed columnar rectangular mesophases. By the time-resolved microwave conductivity method, the columnar rectangular phase of 8 b was shown to exhibit a moderate charge-carrier mobility of 0.12 cm(2) V(-1) s(-1) . These results indicate that large graphyne fragments can serve as good organic semiconductors.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 98%

Syntheses and Properties of Graphyne Fragments: Trigonally Expanded Dehydrobenzo[12]annulenes

Tahara

Yamamoto

Gross

et al. 2013

Chemistry A European J

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“…This compound demonstrates rectangular columnar (Col r ) mesophase over the temperature range 85-101 °C whereas a columnar hexagonal Col h phase was observed in the temperature range 101-152 °C (Table 16) (Table 15) have been synthesized and studied [92]. Table 15 Table 16 A summary of DSC data is presented in Table 16, while Table 4) to demonstrate an example when the alignment of one and the same material can be switched by a simple change of a solid substrate from a hydrophilic to hydrophobic one [93,94]. Typically, homeotropic alignment occurs during annealing at temperatures slightly below transition from the isotropic liquid to the LC mesophase, when the viscosity of the mesophase is the lowest.…”

Section: Table 14mentioning

confidence: 99%

Liquid crystalline metal phthalocyanines: Structural organization on the substrate surface

Basova

Hassan

Durmuş

et al. 2016

Coordination Chemistry Reviews

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The use of metallo phthalocyanines (MPcs) in technological applications requires certain methodological approaches for thin film fabrication. Among these applications is the implementation of MPc films in electronic devices such as organic field-effect transistors (OFETs) and photovoltaic (PV) devices. For such applications the control of alignment and ordering of MPc molecules within the films remains a considerable challenge. This review provides an overview of films' growth of mesogenic MPcs offering systematic analysis of the influence of different factors on the structural organization of liquid crystalline phthalocyanine films, including phthalocyanines molecular structure, regimes of heating, substrate materials, and type of interfaces. The achievements in the development of methods and approaches for the formation of liquid crystalline phthalocyanine films with controllable alignment and ordering are discussed in sufficient details.

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“…The discotic LCs derived from π‐conjugated azaheterocycles are shown to be promising in the context of all aforesaid technical concerns . A wide variety of such discotics, including triazine, hexazatrinaphthylene,„ hexazatriphenylene, oxadiazole, thiadiazoles, triindoles, phthalocyanine,„ porphyrin, and so on, have been synthesized, and their important characteristics in terms of applied science have been studied. However, in the last few years, a considerable amount of attention has been devoted to the synthesis of C 3 ‐symmetric discogens, which includes lyotropic systems as well .…”

Section: Introductionmentioning

confidence: 99%

s‐Triazine‐Based Functional Discotic Liquid Crystals: Synthesis, Mesomorphism and Photoluminescence

et al. 2016

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A new series of C3 -symmetric, π-conjugated molecules was designed, synthesized and characterized. The materials were derived from electron-accepting s-triazine, appended covalently to electron-donating styrylbenzene arms, and were readily prepared in excellent yield with high purity by means of three-fold condensation of triphosphonate with n-alkoxybenzaldehydes under Horner-Wadsworth-Emmons reaction conditions. Examination of the phase transitional properties by several complementary techniques evidenced self-assembly into a hexagonal columnar phase, occurring over wide and reasonable thermal ranges. The photophysical properties were studied both in solution and in the fluid/frozen columnar states by UV/Vis absorption and photoluminescence spectroscopy. The emission spectra obtained as a function of the temperature rule out the breaking-up of larger columns and a non-radiative, thermally activated process. A study carried out on thin films of the glassy columnar state, which accounts for conserved fluorescence, defect-free orientation, and freezing ionic species, with the help of atomic force microscopy (AFM) images, suggested a homogeneous granular morphology comprising fibrillar structures. Dissimilarities in the surface morphology and birefringence of thin films of the solid and frozen columnar states were clearly shown by Raman spectroscopy. An electrochemical investigation revealed a LUMO energy of -4.0 eV. Thus, the discotic motifs presented herein meet certain criteria of organic materials, which are essential for developing electronic devices.

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Transition temperature engineering of octaalkoxycarbonyl phthalocyanines

Cited by 23 publications

References 26 publications

Syntheses and Properties of Graphyne Fragments: Trigonally Expanded Dehydrobenzo[12]annulenes

Syntheses and Properties of Graphyne Fragments: Trigonally Expanded Dehydrobenzo[12]annulenes

Liquid crystalline metal phthalocyanines: Structural organization on the substrate surface

s‐Triazine‐Based Functional Discotic Liquid Crystals: Synthesis, Mesomorphism and Photoluminescence

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