Self-assembled monolayers (SAMs) of 4,4'-terphenyl-substituted alkanethiols C6H5(C6H4)2(CH2)n-SH (TPn, n = 1-6) on Au (111) substrates were studied using scanning tunneling microscopy (STM) and infrared reflection absorption spectroscopy (IRRAS). When the SAMs were prepared at room temperature (RT, 298 K), TPn films (except TP2) exhibit an odd-even effect regarding both molecular orientation and packing density. For all investigated films, STM data reveals the presence of a large degree of lateral order. In the case of odd-numbered TPns, the films revealed a (2 square root(3) x square root(3))R30 degree molecular arrangement. For the even-numbered TP4 and TP6 SAMs, a c(5 square root(3) x 3) rectangular unit cell was found. The packing density for the even-numbered TPn SAMs is 25% lower than that for the odd-numbered TPn SAMs. When the SAMs were prepared at 333 K, the even-numbered SAMs were found to form structures with a significantly lower packing density. In the case of TP2, instead of the (2 square root(3) x square root(3))R30 degree structure formed at room temperature, a c(5 square root(3) x 3) structure was observed. For TP6 SAMs, the room-temperature c(5 square root(3) x 3) structure was replaced by a (6 square root(3) x 2 square root(3))R30 degree structure.

Chemical synthesis of selenoacetic acid Se-anthracen-2-yl ester. 2-Bromoanthracene (1.13 g, 4.39 mmol) [1] was dissolved in THF (80 ml), cooled down to -78°C and tert.-butyllithium (5.9 ml, 8.9mmol) was added to this dropwise. After stirring during warming up to 0°C and cooling back to -78°C, black selenium powder (0.35 g, 4.4 mmol) was added. Again stirring upon warming up was done, following by addition of acetyl chloride (0.35 g, 4.5 mmol) into the cooled solution. Upon further stirring at room temperature, a colorless precipitate was formed. After adding water (100 ml), the aqueous phase was extracted with dichloromethane and the resulting organic phase washed with water (200 ml). After removal of the solvent in vacuum the crude yellow product (1.69 g) was subjected to column chromatography (silica, dichloromethane (5%-100%) / petrol ether, then silica, ethylacetate (5%-100% / petrol ether) and recrystallized from toluene yielding a yellow solid (0.40 g, 1.3 mmol, 30% 197.02, 135.86, 132.23, 131.89, 131.76, 131.30, 130.80, 129.01, 128.25, 128.15, 126.49, 126.32, 125.87, 125.74, 123.74, 34.17. . For background compensation all data were normalized by subtraction of a spectrum which was

Self-assembled monolayers (SAMs) fabricated on Au(111) substrates from a homologous series of pyridine-terminated organothiols have been investigated using ultra high vacuum infrared reflection adsorption spectroscopy (UHV-IRRAS), X-ray photoelectron spectroscopy (XPS), scanning tunnelling microscopy (STM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. A total of 4 different pyridine-based organothiols have been investigated, consisting of a pyridine unit, one or two phenyl units, a spacer of between one and three methylene units and, finally, a thiol unit. For all pyridine-terminated thiols the immersion of Au-substrates in the corresponding ethanolic solutions was found to result in the formation of highly ordered and densely packed SAMs. For an even number of the methylene spacers between the SH group and the aromatic moieties, the SAM unit-cell is rather large, (5sq.rt(3) x 3)rect, whereas in case of an odd number of methylene units a smaller unit cell is adopted, (2sq.rt(3) x sq.rt(3))R30 degrees. The tilt angle of the molecules amounts to 15 degrees . In contrast to expectation, the pyridine-terminated organic surfaces exposed by the corresponding SAMs showed a surprisingly strong resistance with regard to protonation.