Spectroscopic and X-ray diffraction study of Langmuir–Blodgett films of some 1,4,8,11,15,18-hexaalkyl-22,25-bis(carboxypropyl)phthalocyanines

Abstract

Molecular assemblies within Langmuir-Blodgett (LB) fi Ims of 1,4,8,11,15,18-hexaoctyl-22,25-bis(carboxy-propy1)phthalocyanine (la) copper 1,4,8,11,15,18-hexanonyl-22,25-bis(carboxypropyl)phthalocyaninate (lb) and 1,4,8,11,15,18-hexadecyl-22,25-bis(carboxypropyl)phthalocyanine (lc) have been examined using X-ray diffraction, RAIRS and polarised optical spectroscopy. The LB films are constructed as bilayers by Y-type deposition and the resulting assemblies give rise to visible-region absorption spectra closely similar to those of crystallised films of octaalkylphthalocyanines. When heated, the molecular assemblies within the LB films of l a and l b reorganise irreversibly to a form in which the bilayer spacing is reduced. The transition from one type of packing to another is sharp for the film of l a but occurs over a wide temperature range for the film of l b . Heating the film of l c to 140°C modifies the packing but in this case a further modification occurs on cooling.

Non-uniformly substituted phthalocyanines and related compounds: alkylated tribenzo-imidazolo[4,5]- porphyrazines

“…max 765 and 635 nm [43]. This type of splitting of the Q band envelope of phthalocyanine thin films has been attributed to Davydov splitting arising from columnar herring-bone arrangements of the molecules within the film [19,20,43].…”

“…The 3:1 Pcs of series 1 and 2 are ideal materials for depositing as Langmuir-Blodgett (LB) films [15,19,20]. These films are well ordered as judged from X-ray reflectivity measurements, with the molecules deposited anisotropically as shown from polarized light absorption spectroscopy, polarized FTIR spectroscopy [15] and by AFM [21].…”

Synthesis and characterization of novel soluble phthalocyanines with fused conjugated unsaturated groups

“…The precipitate was washed several times with cold water methanol and ethanol to remove the unreacted starting materials and dried in vacuo. After being dried in vacuum, the crude dark green product was isolated with column chromatography over silica gel using CHCl 3 Compound 5 (40 mg, 0.032 mmol) was dissolved in CHCl 3 (6.5e7.0 mL) and CH 3 I (15.66 mg, 0.11 mmol) was added to this solution. The mixture was refluxed for 6 h. Then the mixture was filtered and the precipitate was washed with CHCl 3.…”

“…The presence of a pelectron system is essential for charge-carrier transport, so they exhibit a number of unique properties, which make them of great interest in various scientific and technological areas ranging from nanotechnology to medicine [1]. There has been growing interest in the use of phthalocyanines in a variety of new high technology fields including semiconductor devices [2], LangmuireBlodgett films [3], electrochromic display devices [4], gas sensors [5], liquid crystals [6], nonlinear optics [7], information storage [8], organic light emitting diodes (OLED) [9], photodynamic cancer therapy [10,11] and various catalytic processes [12]. At the present time, great efforts are devoted to the introduction of phthalocyanine moieties into conjugated oligomers and polymers, e.g.…”

Metallophthalocyanines with rod-shaped substituents

“…Apart from these important properties, phthalocyanines find commercial applications as a photoconductor in Xerography [3] and in optical data storage as the laser absorption layer within recordable compact discs [4]. In addition, phthalocyanines are widely studied for applications in non-linear optics [5,6], Langmuir-Blodgett films [7], gas sensors [8], photodynamic cancer therapy [9], electrocromic displays [10,11] and fuel cells [12]. Another useful property of phthalocyanines is their ability to form different kinds of condensed phases such as discotic liquid crystals.…”