Langmuir-Blodgett films of mesogenic porphyrin derivatives

Self-organization of a sulfonamido-porphyrin in Langmuir monolayers and Langmuir–Blodgett films

“…11 As in the previous work, the p-A isotherm of PC12 clearly shows three main regions: the low surface pressure region, normally called the expanded monolayer, the long transition at intermediate surface pressures and condensed regimes at high surface pressures. This same feature is reported for other porphyrins 9,10,20,23,25 and also for phthalocyanines. 8 The monolayers of pure PC12 and mixed with SHS were prepared and their surface pressure-area (p-A) isotherms on water subphase were measured.…”

“…The common orientation of an amphiphilic porphyrin in monolayers is a tilted geometry to the interface. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Assuming that the difference between the value of the molecular area observed for PC12 in the low pressure region of the p-A isotherm (A 0 ¼ 290 A ˚2), and the calculated value (376 A ˚2), is due to the tilting of the porphine ring at the interface, a tilted angle of 39.51 is obtained. In fact, this value lies within those observed for a series of nitrophenyl-amido substituted porphyrins where the tilted angles are 32 to 481.…”

“…Stable LB films of pure tetra-arylporphyrins are observed when the dye is covalently linked to long aliphatic chains (lipophilic porphyrins). [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] The stability of lipophilic porphyrin films is, in general, improved when the dye is spread in the presence of amphiphilic molecules. 9,10,[23][24][25] Also, it has been observed that stable monolayer films are produced with hydrophilic porphyrins either charged [26][27][28] or neutral 29 in an association to ionic and long alkyl chain surfactant molecules at the interface whereas hydrophobic porphyrins do not form stable monolayers.…”

Atypical Behavior of a New Dialkyl Macrocycloureide in Langmuir−Blodgett Film Formation

“…The presence of a plateau could also suggest that because of the tendency of the macrocycloueride moiety to stack, the orientation of DSM molecules at the air/water interface could be modified during the compression. Indeed, it has been shown that for peculiar compounds as porphyrin derivatives, the compression brings them closer with changing their orientation . It was reported that for compounds as cyanine derivatives, which can take several positions, if the compression rate is rapid, the presence of the plateau corresponds to a metastable state with a molecular rearrangement from a flat position at low pressure to an edge-on position at high pressure .…”

Langmuir−Blodgett Films of Metal Complexes of 4-(10,12-Pentacosadiynamidomethyl)pyridine: A Structural Investigation

“…In principle, the metal ions can be incorporated into the monolayer film in two ways. First, by means of salt or complex formation by the amphiphile from the subphase wherein the metal ions are dissolved, and second the metals could be bound to the amphiphile before spreading the formed salt or the metal complex at the air−water interface. , Dithiooxamides, , pyridines, , porphyrines, and phthalocyanines , are often used as ligands for complex formation with metal ions. When crown ethers and imidazoles are used as ligand units in amphiphiles, even at very low subphase concentrations (10 -6 M), metal ions are incorporated into the floating monolayer at the air−water interface, as was shown by Lednev and Petty and van Esch et al Also, metal ions could be incorporated into floating polymer monolayers with an amphiphilic character that have ligand groups such as pyridine, bipyridine, or crown ethers …”