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Background: Detailed photochemical and photocytotoxicity studies of two new porphyrins: 5,10,15,20-meso-tetrakis-(4-acetoxy-3-methoxyphenyl) porphyrin (P2.1) and 5-(4-hydroxy-3- methoxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin (P2.2) are reported, as potential candidates for theranostics. For powdered samples of P2.1 and P2.2 adsorbed onto a powdered biocompatible substrate, polyethylene glycol (PEG), a concentration study was performed, correlating the fluorescence emission intensity with sample absorption to determine the useful concentration range for photodynamic therapy of cancer (PDT) in which aggregation does not occur. Cytotoxicity studies were performed in dark and illuminated conditions. Methods: The laser induced luminescence set-up is home-made, a N2 laser is used as the excitation source and a time gated charged-coupled device (ICCD) as the detector. Fluorescence lifetime determinations were made using pulsed light sources from the excitation LEDs and measures of the fluorescence intensities at different time delays after the excitation pulse. The singlet oxygen formation quantum yields ΦΔ measurements were obtained by comparing the total area of the emission spectra for the reference compound and also for the samples under study in the same solvent and with the same optical density at the excitation wavelength (405 nm). An integrating sphere for relative and absolute measurements was used in this work as an alternative methodology to obtain the values for the fluorescence emission quantum yields (ΦF) of the adsorbed porphyrin under study. The cytotoxicity evaluation was made in the dark and under irradiation, using four different human tumor cell lines and one non-tumor primary cell culture. Results: In order to establish the useful range of concentrations of the sensitizer for PDT, and due to the use of powdered samples, a special methodology was needed: the variations of the fluorescence lifetimes and fluorescence quantum yields were evaluated as a function of the concentration of the dye, measured by (1-R)*fdye. Both ΦF and τF are constant in the range from 0.002 to about 0.050 μmol g-1, and only after that a concentration quenching effect becomes visible, decreasing both ΦF and τF. This methodology is based in the correlations established between the Remission Function values and ΦF and τF obtained for increasing values of the sensitizer concentrations. Conclusion: The study of the aggregation effects of P2.1 and P2.2 porphyrins into a PEG matrix allowed us to determine the usable concentration range for photodynamic therapy use, where the aggregation of porphyrins decreases, therefore reducing the PDT action. The use of an integrating sphere for relative and absolute measurements of fluorescence quantum yields and also the lifetime studies as a function of the dye loading confirms the useful range for the use of P2.1 and P2.2 in PEG as powdered samples. The determination of the GI50, the porphyrin concentration which inhibits 50% of the cell growth, evidences that P2.2, the A3B porphyrin overtakes P2.1 (the A4 porphyrin) in terms of PDT efficiency and both porphyrins are much better PDT agents than the unsubstituted porphyrin, TPP. These data clearly show that porphyrins P2.2 and P2.1 exhibit an excellent behaviour in terms of its photocytotoxicity. These results encourage us to pursuit in the study of this family of porphyrins in which a balance of hydrophobic versus hydrophilic substituents in the phenyl group was achieved.

A detailed archaeometric study of Phoenician ceramics found in an excavation inside the medieval walls of Sao Jorge's Castle in Lisbon is described here. Thirty ceramic sherds were studied, grouped into six categories, namely amphorae, containers for domestic use, red slip wares, grey wares, cooking wares and also some indigenous tradition handmade wares. Micro-Raman, X-Ray Fluorescence Emission, X-Ray Diffraction and ground state diffuse reflectance absorption measurements were correlated and used as our main analytical techniques to perform this study. At least three totally different local clay sources were used to produce the here studied pottery, one of alluvial origin using clays collected along the river banks, and another one using clays probably extracted in the oriental part of the Castle's hill. Cooking-ware was made with the use of raw materials with sandy detrital origin. Evidence was also found showing that part of the amphorae, common containers, and grey wares were made with the same raw materials as used in the Phoenician kilns of Almaraz, located in the left margin of the Tagus River, roughly facing Lisbon's Castle hill. The temperatures of the kilns used to fire the amphorae and common containers was in most cases higher than the one used for firing red slip and grey tableware. A detailed laboratorial study of the alluvial clays fired at different temperatures and collected in the Tagus River banks, allowed us, in most cases, to establish the origin of the sources used to produce the Phoenician pottery found in Lisbon.

In this study, cotton fabrics decorated with Ag/AgCl and Ag/AgBr NPs were produced by a simple hydrothermal treatment using AgCl and AgBr as precursors. Their morphological features as well as, chemical composition and structural and luminescence properties were compared. Their water disinfection aptitude against E. coli and S. aureus was also investigated under solar illumination in batch as well asin dynamic conditions. The highest activity was observed for Cot-Ag/AgCl with a quasi-complete inactivation of E. coli and S. aureus(1.5 × 107cfu mL−1) within 15 min illumination. Disinfection efficiency under continuous flow was also tested using a home-made photoreactor and the cotton fabrics with the most efficient photocatalyst (Ag/AgCl). It has shown to be efficient at least for 10 cycles revealing the robustness of the functionalization. The mechanism of photocatalytic disinfection was explained in terms of the surface plasmon resonance (SPR) induced by the presence of Ag NPs, the resulting holes, h+, being one of the most intervenient species in the disinfection mechanism. The difference in the photocatalytic efficiency between AgCl and AgBr functionalized cotton was attributed to differences in the carriers (h+and e-) lifetime. This work provides a proof of concept for the potential applicability of Cot-Ag/AgCl or Cot-Ag/AgBr for in-flow potabilization of water under solar illumination.

The study reports a series of results obtained by synthesis, spectral and morphological analysis of new tetrapyrrolic structures: 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), Zn(II)-5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Zn(II)1.2) and Cu(II)-5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Cu(II)1.2), as potential candidates for theranostics. Porphyrins were obtained by microwave synthesis under solvent-free conditions and characterized by elemental analysis, FT-IR, UV–Vis and NMR spectroscopies. The absorption properties of the synthetized compounds were studied in different solvents (ethanol, polyethylene glycol 200, dimethylsulfoxide, dichloromethane, chloroform). The spectral profile of the new porphyrins was completed by studying the fluorescence emission and singlet oxygen formation quantum yields. P1.2 and Zn(II)1.2 exhibit fluorescence while for Cu(II)1.2 the fluorescence emission is negligible. P1.2 and Zn(II)1.2 exhibited photodynamic therapy (PDT) acceptable values of singlet oxygen generation. In the case of Cu(II)1.2 this parameter is reduced ca. 5 times. For powdered samples of P1.2 adsorbed onto powdered PEG a detailed study was performed correlating the fluorescence emission intensity with sample absorption to determine the concentration range where aggregation does not occur. Fluorescence emission quantum yields and lifetimes were determined for all samples under study to determine the useful range of concentrations for PDT use. Atomic force microscope (AFM) studies were also made, which exhibit the aggregate species formation for high loadings of the porphyrin P1.2 adsorbed onto specific surfaces.

The archaeological site of Almaraz is located in the old part of the city of Almada, in the south shore of Tagus River, region of Lisbon. The excavated findings and the radiocarbon dating of the contexts where these were found show an occupation that can in fact be dated from the 8th to the 7th c. BCE period, thus a very early stage of the Phoenician occupation in the Iberian Peninsula. Numerous amphorae sherds were found at Almaraz. A spectroscopic characterization of those ceramics was made and is presented here, to help us understand if they were produced locally, in Lisbon workshops, or imported. Sixteen sherds representative of the thousands found at Almaraz were studied with the use of non-invasive spectroscopies, namely by crossing information from micro-Raman and X-ray fluorescence emission data. X-ray diffraction experiments were also performed. In spite of the fact that no ceramic kilns were found at Almaraz until now, the results point to two major groups of amphorae of local origin: one which used clays of Miocene origin, found on the southern shores of the Tagus River, very close to the Almaraz site, at Palenca (with quartz, anorthite, diopside and hematite). Another group, remarkably different, made use of clays of Pliocene origin also from the Tagus Estuary, the Fontainhas clay source (where quartz, anorthite, muscovite and hematite were found).

Silves Castle is located in the Algarve, South of Portugal. Archaeological excavations provided numerous remains of the Islamic presence in this area from the 8th to the 13th c., which could be traced back to the Ommiad, Caliphal, Taifa, Almoravid and Almohad periods. The spectroscopic study of the ceramics, enabled us to discuss their provenance and production techniques. A clear difference in the diffraction patterns of the sherds from the Ommiad period (8th to 9th c.), and the Caliphal period (10th–11th c.) was observed, pointing to imported ceramics in both groups, the latter most likely from Medinat al-Zahra. The origin of the Ommiad ceramics still remains controversial. The samples from the Taifa kingdoms (11th c. period) were characterized as Lisbon productions. The blue and white ceramics studied here (12th–13th c.) are most probably the first samples showing the use of cobalt blue onto a white tin oxide layer made in Portugal.

A detailed archaeometric study of pottery was made of a fifteenth-to-sixteenth-century kiln located inside the walls of the Castle of Alenquer. The locally collected sherds are lead glazed, and mostly exhibit a green or dark yellow decoration. Only in one case, a fragment of a bowl, tin oxide was detected in the white glaze. Pastes from the ceramics of the Alenquer kiln were spectroscopically characterized in terms of their mineralogical and elemental composition. This pottery was fired twice, the first time at high temperatures to produce the biscotto, and the second time at lower temperatures to glaze the ceramics. Although only one type of raw material collected locally was used, two types of ceramic pastes were detected and organized into two groups: one produced at about 850 °C and another at about 950 °C. Pastes from Group 1 were converted into Group 2 pastes whenever the temperature of the kiln was raised from 850 to 950 °C, as confirmed by firing Group 1 pastes in an oven. These results were compared with those obtained for coeval ceramics, namely at Santo Antonio da Charneca and Mata da Machada. Both kilns were located on the south shore of the river Tagus (Lisbon), as previously reported. The first archaeometric study of ceramics produced in the kiln of Alenquer, (Portugal, fifteenth to sixteenth centuries) is reported, with the use of surface spectroscopies techniques, namely micro-Raman. Significant differences were found from two coeval kilns also located at the Tagus basin, Santo Antonio da Charneca and Mata da Machada.

The oldest kilns producing tin glaze wares discovered in the region of Lisbon were located in the south shore of Tagus river at Santo Antonio da Charneca (SAC) and Mata da Machada (MM). Firing this type of pottery from the fourth quarter of the 15th century to mid-16th century, they were located about 20 km away from central Lisbon. Many other examples of ceramics produced in Lisbon workshops from that period are also known and exist in museums or archaeological collections, in spite of the fact that only one kiln dated from that period was found in Lisbon until now. Therefore, the spectroscopic characterization of ceramics found in Lisbon archaeological contexts (attributed to Lisbon workshops) – and also from SAC or MM – was needed and was performed here. Sherds representative of these faience production centres in the Lisbon region dated from the 16th/17th centuries were studied with the use of non-invasive spectroscopies, namely micro-Raman, Ground State Diffuse Reflectance Absorption (GSDR) and X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. Also clays were collected both in the North and South shores of the river Tagus, as much as possible from the same clay sources as used in the initial workshops. The obtained results evidence a clear similarity in the pastes of the pottery of the Lisbon region, quartz, gehlenite and diopside (or augite) being the major components. Clays are from Miocene origin, but differences between the ceramic pastes were detected pointing to the use of several clay sources. The spectroscopic trend exhibited at SAC and MM pottery is remarkably different, quartz being the major component of those pastes, and clays are from Pliocene origin.

Squaraine dyes have recently attracted interest as potential second generation photosensitizers for photodynamic therapy. Several cationic aminosquaraine dyes bearing benzoselenazole terminal nuclei were synthezised and their cytotoxic activity was tested against four different human tumor cell lines – breast (MCF-7), non-small cell lung (NCI-H460), cervical (HeLa) and hepatocellular (HepG2) carcinomas – and against a non-tumor porcine liver primary cell line (PLP2), both in the absence of light and under irradiation. All dyes, which displayed strong absorption within the phototherapeutic window, were found to exhibit photodynamic activity and were shown to be, in most cases, more cytotoxic, both in the dark and upon irradiation, than their benzothiazole analogues. The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and the FEDER for CIMO (UID/ AGR/00690/2013) and CQ-VR (UID/QUI/00616/2013) financial support. info:eu-repo/semantics/publishedVersion

This study reports a surface photochemistry behaviour of two tetrapyrrolic structures: 5,10,15,20-tetra-(4-carboxymethylphenyl) porphyrin (P1.1) and 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), covalently bound to silica-coated magnetite nanoparticles (Fe3O4@SiO2) imbibed into a polyethylene glycol (PEG) matrix and in the form of a fine powder. The initial compounds and the nano-hybrids imbibed in the PEG matrix were characterized using Fourier transformed infrared spectroscopy (FT-IR), diffuse reflectance absorption spectroscopy for ground state molecules (GSDR), X-ray diffaction (XRD), transmission electron electron microscopy (TEM) as well as several luminescence emission spectroscopies. The combined use of these methodologies enabled us to obtain a surface photochemistry characterization of these new nano-hybrid materials. For the powdered samples of P1.1 or P1.2 and Fe3O4@SiO2 imbibed into the powdered PEG a detailed absorption study and a correlation of fluorescence emission intensity with the magnetite concentration were performed. New covalent bonds porphyrin-Fe3O4@SiO2 were detected using FT-IR transmission spectra. A donor-acceptor interaction with change of the oxidation level of the porphyrins was also observed. Fluorescence emission quantum yields and lifetimes of the two porphyrins were determined for all samples and two populations of the porphyrin molecules exist, free porphyrin (unquenched) and porphyrin with Fe3O4@SiO2 NPs attached, the quenched porphyrin. In this way, the amount of the available excited porphyrin for singlet oxygen formation is reduced, therefore the presence of the Fe3O4@SiO2 NPs may not favor this specific PDT action by the Type II mechanism, but it prevents aggregation of the porphyrins, even when a PEG matrix is used, and Type I mechanisms remain active.

The first archaeological evidence reported for tile production in Portugal was discovered in Santo Antonio da Charneca (SAC), late 15th or early 16th centuries' pottery kiln, south riverside of Tagus River. Samples from this kiln were studied with the use of non-invasive spectroscopies, namely, μ-Raman, ground-state diffuse reflectance absorption, Fourier transform infrared and particle-induced X-ray or X-ray fluorescence emission. These results were compared with the ones obtained for coeval tiles produced in Seville, Spain, originated from Portuguese archaeological sites, because it is well know that the Portuguese King Manuel the First imported in 1498 significant quantities of those tiles to decorate several palaces. The obtained results provided new spectroscopic insights, used to establish similarities but also clear differences regarding the SAC and the coeval Seville tiles found in Portugal. White glaze from both tiles gave evidence about the use of tin oxide as whitening agent and lead oxide as glassy agent. Cobalt oxides were also used as blue pigments in the two production centres. The brown and amber pigments in the samples from SAC derive from the manganese oxides dispersed in the lead–tin glaze, and kentrolite crystals were identified by μ-Raman in these tiles. In the arista and cuerda-seca tiles from Seville, diopside was detected. Divalent copper also exists in the green glaze matrix but in small amounts, which did not allow the Raman detection of the copper compound's microcrystals. However, diffuse reflectance measurements point to malachite green as responsible of green coloration. The Seville pastes contain calcium carbonate, although the SAC pastes do not evidence significant amounts of that compound in its composition. All the SAC pastes evidenced a high silica level, and quartz and anatase were clearly detected in the paste and possibly kaolinite. The Raman signals of orthoclase and calcium carbonate were detected in the Seville tiles. Copyright © 2014 John Wiley & Sons, Ltd.

Sherds representative of the Portuguese faience production of the early-16th century from the “Mata da Machada” kiln and from an archaeological excavation on a small urban site in the city of Aveiro (from late 15th to early 16th century) were studied with the use of non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE). These results were compared with the ones obtained for two Spanish productions, from Valencia and Seville, both from same period (late 15th century and 16th century), since it is well know that Portugal imported significant quantities of those goods from Spain at that time. The obtained results evidence a clear similarity in the micro-Raman spectrum in the glaze and clays of Portuguese pottery produced at “Mata da Machada” and sherds found at the mediaeval house of Homem Cristo Filho (HCF) street at Aveiro. The blue pigment in the sample from the household of Aveiro is a cobalt oxide that exists in the silicate glassy matrix in small amounts, which did not allow the formation of detectable cobalt silicate microcrystals. White glaze from Mata da Machada and Aveiro evidence tin oxide micro-Raman signatures superimposed on the bending and stretching bands of SiO2. All these are quite different from the Spanish products under study (Seville and Valencia), pointing to an earlier production of tin glaze earthenware in Portugal than the mid 16th century, as commonly assumed.

Two methods were applied for the functionalization of mesoporous silica materials (MCM-41 and SBA-15). For the acidic functionalization with sulfonicpropyl groups a direct synthesis method was used. For the basic functionalization with aminopropyl groups a post-synthesis methodology was used. Sample characterization was performed by small angle X-ray powder diffraction, nitrogen adsorption and desorption and transmission electron microscopy. Direct functionalization has a high impact on the structural characteristics, decreasing BET surface area and changing its pore size distribution. Trans -4 -[( 4 -dimethylamino)styryl]- 1 -methylpyridinium iodide (DSM + ) was used for the acid base characterization of the synthesized materials. Ground state absorption spectra and laser induced time resolved emission spectra have shown the existence of two forms of the probe: DSM + and the protonated, DSMH 2+ . Lifetime distribution analysis confirmed the presence of these two species in all materials, but with different relative amounts depending on the surface characteristics. All these findings clearly show that DSM + is an excellent probe capable of providing important information regarding the internal surfaces of these materials, with channels of nanometer dimensions, namely the different acid properties of the active sites of these silica based hosts.

This work reports the surface photochemistry study of p-hydroxystilbazol adsorbed within nanochannels of MFI zeolites, namely in a series of NaZSM-5 and HZSM-5 zeolites where the surface acidity of the host was varied systematically. Laser-induced room temperature luminescence of air equilibrated solid powdered samples of p-hydroxystilbazol adsorbed onto the two sets of zeolites, revealed the existence of multiple emissions of p-hydroxystilbazol, namely as a broad band centered at about 470 nm all cases where the host surface was highly acidic, while in other cases emissions with maxima at about 410, 530 and 660 nm were also detected. The decay times of the p-hydroxystilbazol emission vary greatly going from solution to entrapment within the nanochannels of the ZSM-5 zeolites and roughly increase by an order of magnitude upon inclusion. A lifetime distribution analysis has shown that the longest lifetime for the p-hydroxystilbazol fluorescence emission exists in the case where the 530 nm type emission was detected, i.e. whenever the hydrophobic character of the host increases. p-Hydroxystilbazol entrapped in the more acidic zeolites emits mainly in the protonated form. However, p-hydroxystilbazol may emit from neutral, protonated and zwitterionic forms in the case of the more hydrophobic zeolites. High energy (266 nm excitation and high fluences of the excitation laser (30 mJ per pulse) enabled us to evidence a 660 nm emissive form assigned to the quinoid derived from the zwitterionic form of p-hydroxystilbazol. Delayed fluorescence of p-hydroxystilbazol was also detected for the HZSM-5 and NaZSM-5 entrapment both at room temperature.

Powdered solid samples of biacetyl within p - tert -butylcalix[4]arene and p - tert -butylcalix[6]arene were studied with the use of diffuse reflectance techniques to observe the formation of inclusion complexes of the diketone (probe) and those solid powdered matrixes. In all substrates, room temperature phosphorescence was obtained in air equilibrated samples. The decay times vary greatly and the largest lifetime was obtained for biacetyl/ p – tert –butylcalix[4]arene, showing that this host cavity well accommodates biacetyl, this way promoting a significant increase of the triplet emission lifetimes of the diketone. Transient absorption spectra of inclusion complexes show the triplet–triplet absorption of biacetyl in the calix[4]arene case, while the ketyl radical formation is observed in the calix[6]arene case. A lifetime distribution analysis has shown a single band, peaking at 1.9 ms for biacetyl/calix[4]arene indicating a unique emissive species and in accordance with an endo inclusion of the probe within the non-polar cavity of the calixarene. Furthermore, in the calix[6]arene inclusion, the lifetime distribution exhibits two maxima peaking at 40 and 174 μs, showing that in this case the probe is emitting in two different environments, a more confined one within the non-polar cavity of the calixarene, while some others probe molecules emit from a location within the polar lower rim, in accordance with an exo- calix complex formation.

This work reports on the synthesis of Li-doped TiO2 nanoparticles using the sol–gel process and solid-state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X-ray diffraction, UV-vis ground state diffuse reflectance absorption spectra and X-ray photoelectron emission spectroscopy. Results showed that samples prepared by sol–gel process and calcined at 400 °C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid-state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li-doped TiO2 prepared via sol–gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency. Copyright © 2010 John Wiley & Sons, Ltd.

An excavation in a 14th c. church at Torres Novas, named Santa Maria do Castelo, provided some green glazed ceramic sherds, archaeologically dated from 14th c. to the 16th c. The town of Torres Novas is located at the center of Portugal, about 100 km north of Lisbon. The obtained results evidence three types of pastes of the pottery: type 1 with Quartz, Illite, Muscovite and Microcline as the main constituents, type 2 with Quartz, Calcite and Gehlenite; and finally type 3 with Quartz, Calcite and Diopside being the major components. Type 1 pastes are related to clay sources of Pliocene origin, and all this pottery was most probably made in Portuguese kilns. However, types 2 and 3 spectroscopic trends are remarkably different, indicating that those ceramics were produced in Seville. All the studied ceramics are lead glazed, and green glazed. In one of the samples from the Seville kiln, Cerusite was the main pigment used to obtain the greenish colouration. In what regards the origin of all samples produced with Pliocene clays, the 16th c. ones were most likely produced in the Santo Antonio da Charneca or Mata da Machada kilns, both located in the south shore of the Tagus river, region of Lisbon. In what regards the green glazed jug rim (14th c.) and the jug spout (15th c.) they could also have been produced in the two mentioned kilns south of Lisbon city, but another interesting hypothesis - due to richness of the decoration - is the production in Lisbon workshops, with the use of Pliocene clays imported by Lisbon potters, now documented both in Lisbon archaeological findings and also in documental sources.

This paper presents time resolved laser induced luminescence (LIL) and diffuse reflectance laser flash-photolysis (DRLFP) studies of solid powdered samples of xanthione (XT) and 4H-1-benzopyran-4-thione (BPT). These thioketones form inclusion complexes with ptert-butylcalix[6]arene (CLX[6]) and p-tert-butylcalix[8]arene (CLX[8]). Room temperature air equilibrated LIL studies for XT/CLX[8] inclusion complex have shown the existence of both fluorescence and delayed fluorescence emission S-2 -> S-0 emissions in the nanosecond and microsecond time ranges, respectively) peaking at ca. 460 nm while phosphorescence peaks at about 670 nm with a half life of about 4 mu s. For the BPT/CLX[8] inclusion complex, the emissions now peak at ca. 450 and 630 nm, respectively. When these two thioketones are included into the CLX[6] nanocavities similar luminescence spectra were detected. The phosphorescence spectra in all cases present a clear vibrational structure characteristic of non-polar environments, in accordance with the non-polar character of the calixarene's cavities. Diffuse reflectance transient absorption spectra revealed in all cases the presence of the triplet state of the thioketones and also of longer lived species. The use of chromatographic methods (GC-MS) allowed us to identify the formation of xanthone, chromone and hydroxy-thio ketones following laser irradiation at 355 or 337 nm. (c) 2006 Elsevier B.V. All rights reserved.

Diffuse reflectance and chromatography techniques were used to study three Ti-MCM-41 solid powders, containing 1%, 2.5% and 8% of Ti, and to investigate the photochemistry of benzophenone adsorbed on their surfaces. The observed ground state absorption, luminescence and transient absorption spectra depend on the Ti content of the solid support. The luminescence intensity of the pure powders and of the solids with adsorbed benzophenone decreases with the Ti content. The benzophenone triplet emission was detected in all solids but its half-lives decrease with the Ti content of the support. Hydrogen-bonded excited benzophenone luminescence is also quenched but was detected only on supports with low Ti percentage. Transient absorption reveals the formation of trapped electrons and the presence of ligand-to-metal charge transfer in the pure solids, under 266 nm excitation. Ti aggregates are present in all used solid supports. Triplet–triplet absorption of benzophenone was observed in all solids under argon atmosphere. Transient absorption due to the OH–benzophenone radical was detected in all conditions and increases with the Ti content of the powder. 2-Hydroxybenzophenone and benzoic acid are the major photodegradation products in air-equilibrated conditions.

Diffuse reflectance and laser-induced techniques were used to access photochemical and photophysical processes of benzil in solid supports, namely p-tert-butylcalix[n]arenes with n = 4, 6, and 8. A comparative study was performed using these results and those obtained with another electronically inert support, silicalite, which is a hydrophobic zeolite. In the latter substrate, ground-state benzil has the two carbonyl groups in an s-trans planar conformation while in the calixarenes a distribution of conformers exists, largely dominated by skew conformations where the carbonyl groups are twisted one to the other. In all substrates, room-temperature phosphorescence was obtained in air-equilibrated samples. The decay times vary greatly and the largest lifetime was obtained for benzil/p-tert-butylcalix[6]arene, showing that this host cavity well accommodates benzil, enhancing its room-temperature phosphorescence. p-tert-Butylcalix[6] and [8]arene molecules provide larger hydrophobic cavities than silicalite, and inclusion complexes are formed with these hosts and benzil as guest; p-tert-butylcalix[4]arene does not include benzil. This probe is deposited outside the calix[41 cavity, in the form of microcrystals. Triplet-triplet absorption of benzil was detected in all cases and is predominant in the silicalite channel inclusion case. Benzil ketyl radical formation occurs with inclusion in calix[6]arene and calix[8]arene. In the three cases, benzoyl radical was detected at long times (in the millisecond time scale). Product analysis and identification clearly show that the main detected degradation photoproducts in all substrates are benzoyl radical derivatives. Calix[6] and [8]arenes are able to supply hydrogen atoms that allow also another reaction, the reduction to benzoin through benzil ketyl radical formation.

Sherds representative of the three Portuguese faience production centers of the 17th century – Lisbon, Coimbra and Vila Nova were studied with the use of mostly non-invasive spectroscopies, namely: ground state diffuse reflectance absorption (GSDR), micro-Raman, Fourier-transform infrared (FT-IR) and proton induced X-ray (PIXE) or X-ray fluorescence emission (XRF). X-ray diffraction (XRD) experiments were also performed. The obtained results evidence a clear similarity in the pastes of the pottery produced Vila Nova and some of the ceramic pastes from Lisbon, in accordance with documental sources that described the use of Lisbon clays by Vila Nova potters, at least since mid 17th century. Quartz and Gehlenite are the main components of the Lisbon’s pastes, but differences between the ceramic pastes were detected pointing out to the use of several clay sources. The spectroscopic trend exhibited Coimbra’s pottery is remarkably different, Quartz and Diopside being the major components of these pastes, enabling one to well define a pattern for these ceramic bodies. The blue pigment from the Lisbon samples is a cobalt oxide that exists in the silicate glassy matrix, which enables the formation of detectable cobalt silicate microcrystals in most productions of the second half of the 17th century. No micro-Raman cobalt blue signature could be detected in the Vila Nova and Coimbra blue glazes. This is in accordance with the lower kiln temperatures in these two production centers and with Co 2+ ions dispersed in the silicate matrix. In all cases the white glaze is obtained with the use of tin oxide. Hausmannite was detected as the manganese oxide mineral used to produce the purple glaze (wine color “vinoso”) in Lisbon.

This work reports a surface photochemistry study of benzophenone within nanochannels of MFI zeolites, in this case a series of H+ and Na+ ZSM-5 zeolites where the acidity of the host is varied systematically. Laser-induced room temperature luminescence of air equilibrated or argon purged solid powdered samples of benzophenone adsorbed onto the two sets of zeolites, which we will name HZSM-5 and NaZSM-5 zeolites, revealed the existence of three different benzophenone emissions. In the nanosecond time range a broad band centred at about 430 nm was detected and its origin was hydrogen bonded benzophenone. A second broad band peaking at about 470 nm and in the millisecond time range was also detected, which was the emission of the protonated benzophenone. Finally a vibrationally structured emission existed (448 nm), the normal room temperature phosphorescence emission of benzophenone. Triplet-triplet transient absorption of benzophenone was obtained for all zeolites under study, and clear evidence for the formation of hydroxybenzophenone radicals was obtained for the NaZSM-5 series (only Lewis acid sites). The more acidic the internal surface the more radical was detected. Other products resulting from a-cleavage of benzophenone were also identified. When the host was HZSM-5 (Bronsted and Lewis acid sites) benzophenone seemed to be less reactive, and no ketyl radicals from benzophenone were detected. All these findings clearly show that benzophenone is an excellent probe which is able to provide important information regarding the internal surfaces of MFI zeolites, namely the different photocatalytic activity of the different active sites of these zealites. The present study is paradigmatic in what regards the host influence on the photochemistry of the guest. (C) 2008 Elsevier Inc. All rights reserved.

This work reports the use of benzophenone, a very well characterized probe, to study new hosts (i.e., modified celluloses grafted with alkyl chains bearing 12 carbon atoms) by surface esterification. Laser-induced room temperature luminescence of air-equilibrated or argon-purged solid powdered samples of benzophenone adsorbed onto the two modified celluloses, which will be named C12-1500 and C12-1700, revealed the existence of a vibrationally structured phosphorescence emission of benzophenone in the case where ethanol was used for sample preparation, while a nonstructured emission of benzophenone exists when water was used instead of ethanol. The decay times of the benzophenone emission vary greatly with the solvent used for sample preparation and do not change with the alkylation degree in the range of 1500–1700 micromoles of alkyl chains per gram of cellulose. When water was used as a solvent for sample preparation, the shortest lifetime for the benzophenone emission was observed; this result is similar to the case of benzophenone adsorbed onto the “normal” microcrystalline cellulose surface, with this latter case previously reported by Vieira Ferreira et al. in 1995. This is due to the more efficient hydrogen abstraction reaction from the glycoside rings of cellulose when compared with hydrogen abstraction from the alkyl chains of the modified celluloses. Triplet-triplet transient absorption of benzophenone was obtained in both cases and is the predominant absorption immediately after laser pulse, while benzophenone ketyl radical formation occurs in a microsecond time scale both for normal and modified celluloses.

Laser-induced luminescence of argon purged and air-equilibrated samples of dibenzo-p-dioxin adsorbed onto three different solid powdered supports, silicalite, cellulose and silica, revealed the existence of both fluorescence and phosphorescence emissions at room temperature. A remarkable difference in transient absorption spectra was found when dibenzo-p-dioxin was included within the narrow internal channels of silicalite: triplet-triplet absorption of dibenzo-p-dioxin was detected in the silicalite case as a host, simultaneous with radical cation formation immediately after pulsed laser excitation (in the hundreds of nanoseconds time scale) while in the case of cellulose and silica as adsorbents, absorption transients arising from 2,2'-biphenylquinone and possibly from the spiroketone were found. For all hosts dibenzo-p-dioxin exhibits a transient band peaking at 330-340 nm in the microsecond and millisecond time scales, which we assigned to the biradical of dibenzo-p-dioxin. Diffuse reflectance laser flash photolysis and chromatographic techniques provided complementary information, the former about transient species and the latter regarding the final products formed after laser irradiation at 266 nm. Product analysis and identification clearly show that the photodegradation products are dependent on the host, the photochemistry being much more rich and complex in the cellulose and silica cases, where the main detected photoproduts were 2,2'-dihydroxybiphenyl and 1-hydroxydibenzofuran. In the case of silicalite as host, which has a channel-like internal structure and reduced space available for the guest dioxin, photodegradation reactions are highly reduced or even inhibited and no photodegradation products were detected. (c) 2006 Elsevier B.V. All rights reserved.

This work reports the use of benzophenone, a very well characterized probe, to study new hosts: two reversed-phase silicas. Laser-induced room temperature luminescence of argon purged solid powdered samples of benzophenone adsorbed onto the two different reversed-phase silicas, RP-18 and RP-8, revealed the existence of a low energy emission band in contrast with the benzophenone adsorbed on 60 A pore silica, where only triplet benzophenone emits. This low energy emission band was identified as the fluorescence of the ketyl radical of benzophenone, which is formed as the result of a hydrogen atom abstraction reaction of the triplet excited benzophenone from the alkyl groups of the surface of the reversed silicas. Such emission does not exist for benzophenone adsorbed onto 60 A pore silica. Room temperature phosphorescence was obtained in argon purged samples for all the surfaces under use. The decay times of the benzophenone emission vary greatly with the alkylation of the silica surface when compared with "normal" silica surface. A lifetime distributions analysis has shown that the shortest lifetimes for the benzophenone emission exist in the former case. Triplet-triplet absorption of benzophenone was detected in all cases and is the predominant absorption in the case of 60 A pore silica, while benzophenone ketyl radical formation occurs in the case of the reversed silicas. Diffuse reflectance laser flash photolysis and gas chromatography-mass spectrometry techniques provided complementary information, the former about transient species and the latter regarding the final products formed after laser irradiation, both at 266 nm or 355 nm. Product analysis and identification show that the degradation photoproducts are dependent on the excitation wavelength, the photochemistry being much more rich and complex in the 266 nm excitation case, where an alpha-cleavage reaction occurs. A detailed mechanistic analysis is proposed.

The photochemistry of benzophenone adsorbed on a channel-type solid support MCM-41 was studied by the use of diffuse reflectance and chromatographic techniques. For comparison purposes parallel studies were also conducted on silicalite and H-ZSM-5. The observed ground state absorption, luminescence and transient absorption spectra and photoproduct distribution strongly depend on the substrate under study. Triplet state luminescence was observed in all solids, hydrogen-bonded excited benzophenone emission was detected on MCM-41 while protonated excited benzophenone luminescence was observed only on H-ZSM-5. Transient absorption showed the triplet state in all solids and formation of the OH benzophenone adduct on MCM-41 and H-ZSM-5. Ketyl radical formation occurs after 355 nm irradiation but is a minor degradation pathway. The formation of transients resulting from the reaction of benzophenone with molecular oxygen was also detected on MCM-41, in air-equilibrated conditions and benzoic acid is the main degradation product. 2-Hydroxybenzophenone is one of the major photodegradation products on MCM-41 and H-ZSM-5. Products resulting from the α-cleavage were also detected under 266 nm irradiation. Benzophenone was found to be very stable in silicalite under all used conditions.

This work reports the surface photochemistry study of alloxazine adsorbed within nanochannels of MFI zeolites, namely in a series of Na+ and H+ ZSM-5 zeolites where the hydrophobic and hydrophilic character of the host varies systematically. Laser-induced room temperature and 77 K luminescence of air-equilibrated solid powdered samples of alloxazine adsorbed onto the two sets of zeolites, which we will name NaZSM-5 and HZSM-5, revealed the existence of a single emission of alloxazine as a broad band centred at about 450 nm in some cases, while in others an emission with a maximum at about 510 nm was detected. The decay times of the alloxazine emission vary greatly going from solution to entrapment within the nanochannels of the ZSM-5 zeolites. In the latter case a lifetime distribution analysis has shown that the longest lifetime for the alloxazine fluorescence emission exists in the case where an isoalloxazine-type emission was detected, i.e. whenever the hydrophobic character of the host increases. Alloxazine entrapped in the more acidic zeolites exists in the form of emissive monomers. However, alloxazine emits both from monomeric and aggregated emissive forms in the case of the hydrophobic zeolites. These data indicate the formation of planar dimers of alloxazine whenever the number of active sites in the zeolite decreases. These dimers have to be formed at the intersections of the zig-zag and linear nanochannels of the zeolite since there is no space available for their formation inside the zeolite channels. The isoalloxazine tautomers are formed due to the existence of alloxazine dimers which may undergo double proton transfer in the excited state, following laser excitation. Delayed fluorescence of alloxazine was also detected for the HZSM-5 and NaZSM-5 entrapment both at room temperature and at 77 K. The present study is paradigmatic as regards the host influence on the photochemistry of the guest.