Langmuir Monolayers of p-(5‘-m-Terphenylyl)benzoic Acid and Its 2‘-Methyl Derivative at the Water/Air Interface

Langmuir Monolayers from Substituted 5′-Phenyl-m-terphenyl Carboxylic Acids

“…The monolayer studies have confirmed that purely aromatic amphiphiles, containing no alkyl chains, are capable of forming stable monolayers at the air/water interface on their own (13)(14)(15)(16).…”

“…The exceptions are represented by Demchak and co-workers (2, 3) who studied p-terphenyl derivatives, and a few reports on the surface behavior of aromatic compounds modified with long alkyl chains, such as 4-cyano-4 -alkyl-biphenyls or terphenyls (4-9), 4 -alkylaniline (10), longchain pyridine derivatives (11), and amphiphilic dye derivatives (12). Recently we have undertaken studies on the surface behavior of carboxylic acids with solely arenic hydrophobic moieties, consisting of nonrigid polyphenyl ring systems (13)(14)(15)(16). These compounds, containing symmetrical triphenylbenzene ring system, are not in-plane, as confirmed by computer modelling studies (15).…”

Structural Modification Influences the Characteristics of Langmuir Monolayers from Aromatic Carboxylic Acids

“…Recently we instituted a project aimed at a systematic investigation of the monolayer properties of a series of aromatic carboxylic acids in which the hydrophobic part comprises an uncondensed, nonrigid ring system whosemain part is the symmetrical triphenylbenzene (5 -phenyl-m-terphenyl). Previously, we showed that the presence of at least four phenyl groups in the apolar core is a prerequisite for the molecule to have the proper hydrophilic-hydrophobic balance necessary for Langmuir monolayer formation (5). Detailed investigations on the basic compound (5 -phenyl-1,1 : 3 ,1 -terphenyl-4-carboxylic acid, in short PTCA, see compound a, Scheme 1) and its 4 derivatives (6-8) demonstrated that they form stable monolayers at the air/water interface on their own, without the need to mix with any builder materials, although these molecules do not have alkyl chains which are generally assumed to be necessary for spreading.…”

Synthesis and Langmuir Monolayer Characterisation of Some Nitro Derivatives of Polyphenyl Carboxylic Acids

“…Our former studies on the surface behaviour of carboxylic acids with only benzenoid aromatic hydrophobic moieties, consisting of non-rigid polyphenyl ring systems, have proved that purely aromatic amphiphiles, containing no alkyl chains, are capable of forming stable monolayers at the airwater interface on their own. [1][2][3] The basic compound for our investigations, i.e. 5'-phenyl-1,1' : 3',1"-terphenyl-4-carboxylic acid, abbreviated as PTCA (Scheme 1), displays on the surface that spans the area corresponding to a ratio of ca 2 between the areas at the start and at the end of the plateau (Fig.…”

“…1). 1,2 Thorough analysis of electric surface potential measurements (that enabled effective dipole moment calculation) together with surface pressure isotherms, complemented with Brewster angle microscope images, allowed us to conclude that the inclination of molecules followed by multilayer formation was the probable cause for the plateau in the isotherm. 2 Since by the structure of molecules, we have also performed studies substituent at the 4'-position [3][4][5][6] as well as on both side rings, 7 on Our results showed that PTCA and its derivatives form stable Langmuir monolayers, transferable onto solid supports.…”