A covalently assembled monolayer of 61-(p-hydroxyphenylmethano)fullerene [C60] molecules has been synthesized. Both static and dynamic contact angle measurements show that the hydrophobic character increases upon the fullerene linkage. Atomic force microscopy lithography shows that the depth of the monolayer is about 19 Å. UV−vis spectra are well-tuned with the presence of the fullerene on the silica surfaces. The surface atomic composition, investigated by angle-resolved X-ray photoelectron spectra, shows a monotonic increase of the carbon signal upon decreasing the photoelectron takeoff angles, thus confirming the upper layer nature of this signal. Room-temperature photoluminescence spectra, under controlled atmosphere, show that the oxygen presence influences considerably the luminescence quantum yield.

The optical gas recognition capability of a covalently self-assembled monolayer of 5,10,15-tri-{p-dodecanoxyphenyl}-20-(p-hydroxyphenyl) porphyrin molecules on silica substrates was studied. The following analytes have been investigated: NO 2 , CO, CH 4 , H 2 , NH 3 , HCl, CHCl 3 , C 2 H 5 OH, CH 3 OH, pyridine, tetrahydrofurane, triethylamine, and dimethylformamide. The self-assembled porphyrin monolayer appears highly sensitive to 1 ppm of NO 2 in both anhydrous and humid conditions. The selectivity of the self-assembled porphyrin monolayer with respect to other analytes was also examined and present data show that the presence of CO, CH 4 , H 2 , and NH 3 does not influence its UV-vis spectrum. Many common solvents slowly affect the position of the Soret band. The presence of HCl vapors results in a broad band extending over the entire 440-500 nm range while the starting Soret disappears. UV-vis measurements on a n-hexane 1.0‚10 -5 solution of the 2, 3,7,8,12,13,17,18-octaethyl-21H,23H-porphine, that does not contain phenyl substituents in the meso positions, show no changes in the optical spectrum upon NO 2 interaction. It emerges that aromatic substituents in the meso positions play a crucial role in determining the optical sensing properties.

Engineering of inorganic surfaces by covalent bonding of organic molecules represents an interesting approach to the synthesis of hybrid inorganic/organic nanomaterials. 1 Few works concerning appropriately functionalized porphyrin molecules bound to different substrates have been already reported and, usually, in the perspective of sensors fabrication. [2][3][4][5] Some studies regarding optical pH sensors based on thin films containing different dyes have already been reported. 6,7 Among these, only a few papers regard the application of porphyrins as pH sensors and none of them deal with a covalently assembled porphyrin monolayer. 7 In fact, the few reported studies focus on incorporation of porphyrin into sol-gel materials, 7a protonation of porphyrins in liquid PVC membranes, 7b electrostatically immobilized porphyrin on the surface of sulfonated polystyrene, 7c porphyrin-coated platinum electrodes, 7d and electropolymerized cobalt porphyrin. 7e In this context, we focused our interest on the 5,10,15-{p-[9-methoxy-3-(oxyethylene)]oxyphenyl}-20-(p-hydroxyphenyl) porphyrin (called P), a chromophore (see Scheme 1) that shows a very high molar absorbance coefficient (1.42 × 10 5 in THF) 8 and a good affinity toward [H 3 O + ] (vide infra). The presence of only one hydroxyl group in the peripheral position of the porphyrin allows an univocal covalent linkage to the substrate. Moreover, the presence of the 3-methoxy-3-(oxyethylene) groups, covalently bound in the remaining peripheral positions of the porphyrin, increases its hydrophilic character.There was, therefore, enough motivation to embark on the fabrication of a P monolayer, covalently assembled on a silica substrate (called P-CAM), and to study its pH sensing behavior for acid solutions. P was synthesized, by a partial condensation reaction between appropriate quantities of the sodium salt of tetrakis-(p-hydroxyphenyl)porphyrin and 3-(oxyethylene) methyl ether chloride. 8a Moreover, it was purified and characterized as already reported. 8a Its pure sodium salt was obtained by reacting a tetrahydrofuran (THF) porphyrin solution with an equimolar amount of a methanol solution of sodium tertbutoxide and removing in a vacuum the tert-butylic alcohol formed during the reaction, THF, and methanol. Three successive steps have been expedient (Scheme 1) for the synthesis of the P-CAM. 4a,9 Fused silica (quartz) substrates (i) were first cleaned with "piranha"solution (cH 2 SO 4 :30% H 2 O 2 70:30 v/v) at 80°C for 1 h and then left to cool to room temperature. 4a,9 They were repeatedly rinsed with double-distilled water and immersed in a H 2 O:30% H 2 O 2 : NH 3 5:1:1 v/v/v mixture at room temperature for 40 min. 4a,9 Then, they were washed with double-distilled water and dried under vacuum immediately before deposition of the coupling agent. All the following sample manipulations have been (1) (a) Gulino, A.; Mineo, P.; Scamporrino, E.; Vitalini, D.; Fragalà, I. Yasseri, A. A.; Loewe, R. S.; Lysenko, A. B.; Malinovskii, V. L.; Zhao, Q.; Surthi, S.; Li, Q.; Misr...

The dependence of the calculated average molecular mass of a polyethylene glycol with a large polydispersity on the instrumental parameters adopted in the acquisition of mass spectra using delayed extraction matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (DE MALDI-TOFMS) was investigated. It has been shown that a combined effect of delay times and potential gradients can act on the ion cloud in the source chamber affecting both mass resolution and average molecular mass value of the analyzed polymeric sample. Also examined was a blend of two different polymers (a PEG and a PMMA commercial sample having a similar average molecular mass), which presents an additional problem concerning the discrimination among the different polymer species as a function of the experimental conditions. In this work, the best instrumental conditions to obtain both good resolution and a correct average molecular mass for the examined polydisperse sample are reported.

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Specific reactions of amino and carboxyl end groups of Nylon 6 with the reactive oxazoline groups belonging to a cyclophosphazene compound (referred as CP2OXA) were carried out at 240 °C for different times, under inert atmosphere. Ny6 polymers terminated with one specific reactive chain end (−COOH or NH2) were reacted with different amounts of CP2OXA to study the kinetic order of the reactions. All Ny6−CP2OXA reacted products soluble in trifluoroethanol (TFE) were well characterized by MALDI−TOF MS, FT-IR and (1H and 13C) NMR techniques. The MALDI−TOF results show that the oxazoline rings react with the carboxyl chain ends of Ny6 following second-order kinetics. The reactions with amino chain ends are very fast and high amounts of gels are produced in just 5 min heating, whereas traces of gel are formed when Ny6COOH and CP-2OXA are reacted for 60 min. The gels were characterized by FTIR analyses, and also by MALDI−TOF MS after partial acid hydrolysis. MALDI−TOF mass spectra reveal also that oxazoline rings can react with −NH amide groups along the Ny6 chains, and with secondary amino groups formed by a condensation reaction involving the elimination of ammonia from two amino chain ends. These side reactions could be responsible of the formation of the gels. The polymerization of CP2OXA was also observed, and the oligomers formed could also react with Ny6 samples during the melt mixing.

The preparation of a bisphenol‐A carbonate copolymer, containing Cu‐diimine units with nonlinear optical (NLO) properties, and its MALDI‐TOF mass spectrometric characterization are reported. Contrary to the usual synthetic method, NLO groups were inserted directly into a commercial polycarbonate by prolonged heating at 250 °C. This innovative procedure allows to obtain a Cu/diimine‐containing polymer of high molecular weight. magnified image

The synthesis of some poly(bisphenol‐A)carbonates (PCs) containing hydrophilic porphyrin units as end groups, by thermal treatment of commercial PC and 5,10,15‐tri{p[ω‐methoxy‐poly(oxyethylene)]phenyl}20(p‐hydroxy phenyl)porphyrin (I) blends, is reported. A suitable choice of reaction temperature, molar composition and reaction time, allowing the extent of the outer‐inner transesterification reactions, leads to a gradual insertion of porphyrin units in the polymer chains. The composition of the obtained materials was inferred by GPC and MALDI‐TOF mass spectrometric analysis.