Holmium porphyrin compound liquid crystals: Synthesis and properties

Yu, Miao; Zhang, Yu J.; Shi, Jian Hui; Liu, Guo F.; Zhang, Hong J.

doi:10.1016/j.solidstatesciences.2009.06.022

Cited by 9 publications

(11 citation statements)

References 38 publications

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“…in the presence of ammonium acetate (8 equiv. ) and La(OTf) 3 (20 mol%). 35 The procedure led to compound 1a in good yield (45%) affording as minor compounds the benzoporphyrin 2a (29%) and the porphyrin-chalcone 3a (10%) ( Table 1, entry 1).…”

Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

“…Our rst experiments with 3-and 4-acetylpyridine, were performed also in reuxing toluene, in the presence of 5 equiv. of these ketones, ammonium acetate and using La(OTf) 3 as catalyst as it was described for 2-acetylpyridine. However, under these conditions and even aer 6 h of reaction, besides the large decomposition observed at the bottom of TLC, the main products isolated and structurally characterized (see below) aer work up and chromatographic purication were the porphyrinchalcone derivatives 3b (33%) and 3c (36%) instead of the desired 2-(terpyridin-4-yl)porphyrin derivatives 1b (16%) and 1c (18%), (Table 1, respectively entries 3 and 5).…”

Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

“…and consequently of ammonium acetate and La(OTf) 3 (Table 1, entries 4 and 6). Under these conditions and aer 4 h of reaction, we were able to isolate derivatives 1b and 1c as the main reactional products and in comfortable yields (45% and 48% respectively).…”

Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

“…The above mentioned processes leading to the formation of the [M CH 3 ] + ion are favoured in the case of ortho isomer due to the higher sterical hindrance induced by the proximity of the methyl substituents.…”

Section: 41mentioning

confidence: 99%

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Synthesis, characterization and biological evaluation of cationic porphyrin–terpyridine derivatives

et al. 2016

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in the beta-pyrrolic positions; the results already obtained show that this type of PSs is also very promising.This fact, and our nding of an easy synthesis for porphyrin 1a (see Fig. 1) bearing a terpyridine unit in the beta pyrrolic position, 35 prompted us to expand the studies to the syntheses of the analogues 1b and 1c in order to use them as templates for further cationization. So, herein, we report the synthesis and the characterization of a series of neutral and cationic porphyrins bearing terpyridine units in one of their beta-pyrrolic positions. In the course of the characterization of these compounds we found that isomer differentiation of the cationic compounds could be easily achieved by ESI-MS (electrospray mass spectrometry).Additionally, their efficacy on the photoinactivation of bioluminescent E. coli was evaluated. The bioluminescent genetically transformed E. coli was selected as a model of Gramnegative bacteria to monitor in real-time photodynamic inactivation through bioluminescence measurement, thus avoiding the laborious and time-consuming conventional method of counting colony-forming units. Results and discussion Synthesis of neutral derivativesThe synthetic strategy to obtain the new b-pyrrolic cationic derivatives 6 and 7 (see Scheme 2) required the previous preparation of the corresponding neutral derivatives according with experimental work summarized in Scheme 1. The access to the new neutral porphyrins 1b and 1c bearing the terpyridine units in the b-pyrrolic positions involved the Kröhnke type approach described previously for the synthesis of porphyrin 1a. 35 In this methodology the terpyridine moiety was built directly from the easy accessible 2-formyl-5,10,15,20-porphyrin (TPP-CHO) 36 by reaction with 2-acetylpyridine (5 equiv.) in the presence of ammonium acetate (8 equiv.) and La(OTf) 3 (20 mol%).35 The procedure led to compound 1a in good yield (45%) affording as minor compounds the benzoporphyrin 2a (29%) and the porphyrin-chalcone 3a (10%) ( Table 1, entry 1).Based on that synthetic strategy we envisaged, just by changing the 2-acetylpyridine by the adequate 3-and 4-acetylpyridine the syntheses of the new neutral terpyridine derivatives 1b and 1c.In order to force the formation of the desired terpyridine 1a, the reaction was repeated in the presence of 2-acetylpyridine during 4 h. The results summarized in Table 1 (entry 2) show that the expected derivatives 1a, 2a and 3a were isolated in yields similar to our previously used conditions. However, a careful analysis of TLC data allowed us to detect a minor and more polar red product. Aer purication, the structure of this product, obtained in 4% yield, was established based on spectroscopic data (see infra and also ESI †) as the new 2-(2,4-diarylpyridin-6-yl)-5,10,15,20-tetraphenylporphyrin 4 (Fig. 2).Attempts to improve compound 4 yield by increasing the reaction time were not successful. The formation of the new derivative 4 can be explained in a similar manner as the one proposed for derivative 1a, 35 using as template...

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Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

Section: Synthesis Of Neutral Derivativesmentioning

confidence: 99%

Section: 41mentioning

confidence: 99%

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Synthesis, characterization and biological evaluation of cationic porphyrin–terpyridine derivatives

et al. 2016

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“…The free base porphyrin 4a have four Q bands denoted as IV, III, II, and I, 32 while the metallated porphyrins presented one (4b and 4c) or two Q bands (4d) due to the increase of symmetry of the complexes. 34 Characteristic Q and B (Soret) bands of metalloporphyrins are determined by transitions of the π-electrons between two higher occupied and two lower unoccupied orbitals. 35 Nevertheless, the changes in the molecular structure and the effect of the solvent may alter the spectra of the porphyrins.…”

Section: Electronic Absorption and Luminescence Spectramentioning

confidence: 99%

Synthesis, Characterization and Dielectric Properties of New 5-(4-Hydroxyphenyl)-10,15,20-tri-4-[2-(3-pentadecylphenoxy)ethoxy]phenyl porphyrin and Their Ni, Co and Cu Complexes

Mota¹,

Júnior²,

Ribeiro³

et al. 2016

J. Braz. Chem. Soc.

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New asymmetric cardanol-based porphyrins, free-base and coordinated with Ni, Co and Cu, were synthesized and completely characterized as A3B type. Such porphyrins were obtained aiming improved solubility in polar solvents due insertion of an −OH phenolic group. Their thermal and dielectric properties were also evaluated. Changes in the synthetic route reduced the reaction time and improved the yields of the aldehyde precursor obtainment. Electronic absorption spectra of the new porphyrins in CH 2 Cl 2 , EtOH and acetone, indicated a decrease in the ε (molar absorptivity) values with increasing solvent polarity, except for the nickel complex which, in acetone, showed a slight increase of 2% in the ε value. The dielectric measurements showed that the conductivity (σ) and the loss tangent (tan δ) increased with frequency, but the permittivity (ε') decreased. The results showed that the coordination of the porphyrin promoted a significant change in thermal and dielectric properties, specially for to the Ni-complex compound, which presented the best dielectric properties with interesting values of permittivity and loss tangent at 100 MHz (19.46 and 0.011 a.u., respectively). Keywords: asymmetric porphyrins, cardanol, dielectric properties IntroductionPorphyrins are relatively planar aromatic system consisting of four pyrrole type rings joined by four methynic carbons. They have attracted scientists from many areas due to their biological importance, their fascinating physical, chemical, and spectroscopic properties.1 These compounds have a high electron density due to its 18 π-electrons delocalized on the macrocyclic ring, which are responsible for their spectroscopic characteristics. 2Porphyrin and its derivatives play multiple roles in nature, such as energy transfer and light absorption in a wide range of the electromagnetic spectrum. Such features are of great interest to the industry of optoelectronic components, such as solar cells, due to its ability to act as photosensitizers when irradiated under visible light.3 Thus, this is certainly one of the most promising areas of application for these compounds. The structural modeling and synthesis of new porphyrins has grown exponentially in order to control their electronic and thermal properties. 4 The addition of substituents at the meso positions and metal ions in the center of porphyrins can improve the electrical and magnetic properties, protecting against auto-oxidation and reducing the formation of dimers. However, these structural modifications can promote, in some cases, a significant decrease in their planarity. 5A simple way to obtain porphyrins is the acid catalyzed condensation reaction of pyrrole with specific aldehyde, followed by oxidation of the porphyrinogen. This procedure, originally developed by Rothemund,6 has been refined by [7][8][9] due to the addition of metal salts to the reaction. Despite the modest yields, the relative simplicity of this method has become suited for preparation of large amounts of tetraarylporphyrins. Higher yields an...

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Self‐Organized Semiconducting Discotic Liquid Crystals for Optoelectronic Applications

Xue

2012

Liquid Crystals Beyond Displays

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Holmium porphyrin compound liquid crystals: Synthesis and properties

Cited by 9 publications

References 38 publications

Synthesis, characterization and biological evaluation of cationic porphyrin–terpyridine derivatives

Synthesis, characterization and biological evaluation of cationic porphyrin–terpyridine derivatives

Synthesis, Characterization and Dielectric Properties of New 5-(4-Hydroxyphenyl)-10,15,20-tri-4-[2-(3-pentadecylphenoxy)ethoxy]phenyl porphyrin and Their Ni, Co and Cu Complexes

Self‐Organized Semiconducting Discotic Liquid Crystals for Optoelectronic Applications

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