Fluorination of polymers containing COOH/COOR groups with SF4/HF, 1. Model reactions with low molecular weight compounds

Model studies with low molecular weight compounds are performed in order to evaluate the feasibility of synthesizing fluorine-containing polymers by modification of commercially available products. The conversion of ? COOH and ? COOR into ? CF₃ moieties by means of SF₄/HF is checked with the following low molecular weight models for poly(acrylic acid) and poly(acrylic ester)s: hexanoic acid ( 1 ), ethyl hexanoate ( 2 ), 2,4-dimethylglutaric acid ( 3 ), 4-carboxypimelic acid ( 4 ) and 2,2-diethylmalonic acid ( 5 ). For the model compounds, the reaction conditions have been optimized. The desired products are obtained in high yield and in high selectivity. Therefore, this type of reaction will be applied to the modification of polymers in the next step.     

Thermal reactions of amphotropic copolymers studied by thermogravimetry and temperature-resolved pyrolysis-field ionization mass spectrometry

The thermal degradation mechanisms of amphiphilic acrylic copolymers containing mesogenic pyrimidine side chains and hydrophilic 2-hydroxyethyl acrylate (HEA) main-chain spacer units were investigated by thermogravimetry (TG) and pyrolysis-field ionization mass spectrometry (Py-FIMS). The degradation behaviour of these polymers depends on the amount of HEA incorporated. Thermogravimetry revealed that the main decomposition occurs in a single step for the pyrimidine homopolymer, whereas with increasing HEA content a two-step process evolves. The major products identified by Py-FIMS are two alcohols and one olefin split from the aromatic side chains. Depolymerization is only a minor degradation pathway. The rather complex thermal behaviour can be explained by three different reaction mechanisms: (a) alcohol formation via reaction of the HEA hydroxyl groups with ester groups in the side chains, (b) intramolecular cis-elimination forming a volatile olefin and carboxylic acid groups remaining at the polymer backbone, and (c) the reaction of these acid groups with ester bonds forming the alcohols. Steps (b) and (c) are dominant for the pyrimidine homopolymer. With increasing HEA content in the copolymers step (a) becomes more important and, in addition, chemical crosslinking occurs. The mesogenic monomer, which was also examined, polymerized under the experimental conditions and showed essentially the thermal features of the pyrimidine homopolymer.     

Synthèse d'homopolymères et de copolymères de la N-acryloyglycine et de l'acide N-acryloyliminodiacétique, 3. Evaluation de leurs propriétés complexantes vis-à-vis de l'ion métallique Cu2+

Homopolymers and copolymers of N-acryloylglycine with acrylic acid and acrylamide were synthetized by radical mechanism using azoisobutyronitrile as initiator in dioxane at 80°C. Moreover, hydrolysis conditions of the ester groups of the diethyl N-acryloyliminodiacetate homopolymers and copolymers with acrylic acid and acrylamide, previously synthetized, have been determined to avoid hydrolysis of the amide functions of the diethyl N-acryloyliminodiacetate and acrylamide units. The obtained macromolecular structures have a density of complexing groups which varies either in the same unit (one or two aminoacetic groups) or along the polymer chain. The influence of this density on the complexing ability of the synthetized polymers for Cu²⁺ was investigated by potentiometry and by visible and ultra-violet absorption spectroscopy.     

Synthesis of Double‐Hydrophilic Block Copolymers with Hydrophobic Moieties for the Controlled Crystallization of Minerals

A set of double hydrophilic block copolymers was synthesized on the basis of a branched poly(ethylene glycol)‐block‐poly(ethyleneimine) (PEG‐b‐PEI) block copolymer by polymer analogous reactions. Different hydrophobic moieties were successfully introduced as well as carboxylate, phosphonate, sulfonate and thiol groups leading to a library of only partially differing block copolymers. The analysis of the block copolymers by GPC turned out to be extremely difficult, as the multifunctional polymers tend to interact with various column materials. However, characterization of PEG‐b‐PEI was possible with ¹H NMR and analytical ultracentrifugation as well as with elemental analysis. These techniques revealed a significant amount of unbound PEG due to side reactions with PEI monomers or oligomers. The degree of the various functionalizations of PEG‐b‐PEI was determined by elemental analysis indicating that the sterically big phosphonic or sulfonic acid groups are only attached to the primary amino groups of the PEI block whereas the smaller thiol and carboxy groups can additionally be bound to secondary amino groups. The set of polymers was applied as additive in the crystallization of CaCO₃ yielding microparticles in all cases. Under the basic conditions of the experiment (pH > 8.5), both hydrophobically modified and unmodified polymers show almost the same influence on the CaCO₃ morphology, whereas the stabilization of the formed microparticles varies. However, the kind of functional group has a strong influence, with phosphonate and sulfonate as the substituents leading to the most significant changes in the CaCO₃ morphology.     

Synthesis of Acrylic Copolymers with Pendant Hydrophilic Groups and Comparative Surface Tension Studies with Corresponding Siloxane Copolymers

Methyl methacrylate (MMA) and methacrylic acid glycidyl ester (MAGE) have been copolymerized and three water‐soluble derivatives of these types of copolymers have been synthesized by opening the epoxide ring with different hydrophilic functional groups like diethanolamine (CHE), quaternary diethylamine (CQDEA) and quaternary diethanolamine (CQHE). The structures have been identified by ¹H and ¹³C NMR spectra. The behaviors in aqueous medium have been investigated in terms of the surface tension and the ratios of intensities of the fluorescence (I₁/I₃). The results are compared with those of the corresponding water‐soluble siloxane copolymers (SHE, SQDEA, SQHE). The plot of I₁/I₃ as a function of polymer concentration verifies the existence of aggregates and indicates the extent of aggregate formation. It is found that the polymer molecules begin to transfer to the air/water interface before they start to form aggregates for both acrylic and siloxane copolymers. It is evident from the surface tension measurements that efficiency of these polymers to reduce surface tension in aqueous solution is in the order SHE > SQHE > SQDEA and CHE > CQDEA > CQHE. The plots of I₁/I₃ as a function of polymer concentration show that the ease of formation of aggregates in aqueous solutions of the above‐mentioned polymers is in the order SHE > SQDEA > SQHE and CHE > CQDEA > CQHE. The ability of aggregates formation in aqueous solution increases with increasing polymer concentration and the hydrophilicity of the hydrophilic moieties. Moreover, the inner core of these copolymer aggregates is less closely packed than those for usual surfactants like sodium dodecylsulfate (SDS). However, the inner cores of the aggregates of siloxane copolymers in solution are more hydrophobic than those of acrylic copolymers.     

Role of hydrophobic interaction in the enantioselective solvolyses of amino acid p-nitrophenyl esters by optically active imidazole-containing polymers

Solvolytic reactions of N-benzyloxycarbonyl-D -phenylalanine p-nitrophenyl ester and N-benzyloxycarbonyl-L -phenylalanine p-nitrophenyl ester by optically active imidazole-containing polymers were performed at different temperatures and in aq. ethanol of different water contents. The catalyst polymers employed were homopolymers of N-methacryloyl-L -histidine ( 1a ) and N-methacryloyl-L -histidine methyl ester ( 1b ), as well as copolymers of 1a with dodecyl methacrylate (DMA) and 1b with DMA. In 30 vol. -% aqueous ethanol at pH 7,02 the homopolymers did not show any enantioselective catalysis. However, the copolymers did exhibit enantioselective catalysis, viz., k_cat(L )/k_cat(D ) = 1,25 for poly ( 1b -co-DMA) containing 5,7 mol-% of DMA. As the reaction temperature was lowered, the reaction rate increased and the enantioselectivity was enhanced (k_cat(L )/k_cat(D ) = 1,67 for poly ( 1b -co-DMA) at 10°C). When the ethanol content was decreased, enhanced reaction rates and enantioselectivity (k_cat(L )/k_cat(D ) = 1,65 for poly ( 1 b -co-DMA) in 20 vol.-% aqueous ethanol) were observed. From these results it is concluded that hydrophobic interaction plays an important role in the enantioselective catalysis of optically active imidazole-containing polymers.     

Effect of Pt(II) coordination on the thermotropic liquid-crystalline behavior of poly(acrylic ester)s containing 4′-cyano-4-biphenylyloxy mesogenic groups

Poly(acrylic ester)s 3a – f and 4a – g , containing 4′-cyano-4-biphenylyloxy mesogenic groups coordinating to Pt(II) ions with various contents, were synthesized by ligand exchange reaction of poly(acrylic ester)s 1 and 2 with dichlorobis(benzonitrile)platinum (II). The effect of Pt(II) coordination of the mesogen on the thermotropic liquid-crystalline behavior was examined by DSC, X-ray diffraction, and polarizing microscopy. For polymers 1 , 3a – c with a content x of 4′-cyano-4-biphenylyloxy mesogen coordinating to the Pt(II) ion less than 24 mol-%, a nematic mesophase was observed between T_g and T_c. For polymers 2 , 4a – e with x < 20 mol-%, a smectic mesophase was found between T_g and T_c. On the other hand, polymers 3d – f and 4 f and g with a high amount of mesogenic groups coordinating to the Pt(II) ion do not form mesophases due to the cross-linked structure resulting from the coordination of the mesogen to the Pt(II) ion.     

Tailored Semiconducting Polymers: Living Radical Polymerization and NLO‐Functionalization of Triphenylamines

This paper describes the preparation of various polymers with triarylamine side groups. High molecular weight materials were obtained by free radical polymerization utilizing the gel effect. Polymers with a narrow polydispersity and a predetermined molecular weight could be prepared by living radical polymerization. The T_g could, thereby, be controlled between 50 and 140°C either by using different monomers or by varying the molecular weight. Living radical polymerization allowed in addition the preparation of block copolymers. The triarylamine side groups could be transformed into NLO‐chromophores by reaction with tetracyanoethylene. This leads to the incorporation of tricyanoethylene acceptor groups. As this reaction can be performed selectively on one block in block copolymers, microphase separated structures are accessible, which possess charge transport moieties in one phase and NLO‐chromophores in the other phase.     

Copolymers from tert‐Butyl Methacrylate with Trimethylsilyl Methacrylate or Methacrylic Acid: Models for Resist Polymers

Free radical copolymerisation of tert‐butyl methacrylate ( 1 ) with trimethylsilyl methacrylate ( 2 ) and methacrylic acid ( 3 ) has been investigated. Reactivity ratios for methacrylic acid and tert‐butyl methacrylate indicate an azeotropic copolymerisation (r ₁ = 0.476 ± 0.103; r ₃ = 0.300 ± 0.032), whereas the two esters show preferential incorporation of 2 (r ₁ = 0.170 ± 0.050; r ₂ = 1.170 ± 0.124). Thermal cis‐elimination of isobutylene from the tert‐butyl ester and subsequent formation of six‐membered cyclic anhydride moieties has been studied. For poly(methacrylic acid‐co‐tert‐butyl methacrylate) thermogravimetry could be used to determine copolymer composition. Solvolytic desilylation of the trimethylsilyl ester groups has been investigated as an alternative route to poly(methacrylic acid‐co‐tert‐butyl methacrylate). The tert‐butyl ester is not affected under the conditions of desilylation. Sequence distribution of both copolymers has been calculated using the method introduced by Bruns and Motoc.

Copolymer composition diagram for tert‐butyl methacrylate/methacrylic acid.     

Tactic copolymers derived from poly(methacrylohydrazide) and functional α-amino acids

Lactic acid and N-tert-butoxycarbonyl protected L-alanine, L-histidine and L-serine were condensed with syndiotactic poly(methacrylohydrazide) (1) in aqueous solution in the presence of N-ethyl-N′-(3-dimethylaminopropyl) carbodiimide. By incomplete conversion of (1) copolymers 4a – d were obtained containing methacrylohydrazide monomeric units. By complete conversion with L-histidine and L-serine simultaneously, copolymers 5 containing both amino acid moieties were obtained. The N-tert-butoxycarbonyl protecting group was removed from the polymers by acidolysis. This reaction was followed by CD spectroscopy. All polymers were characterized by ¹H and ¹³C NMR spectroscopy.     

Simultaneous Substitution of Silicon and Fluorine Atom on Donor–Acceptor Copolymers for Photovoltaic Applications

To investigate the effect of silole‐containing and fluorination on the photovoltaic performance of polymer solar cells, two conjugated donor–acceptor copolymers have been synthesized via Stille coupling reaction. Both donor–acceptor alternating copolymers consisted of 4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b :4,5‐b′ ]dithiophene as the donor unit and nonfluorinated or fluorinated 2,1,3‐benzooxadiazole (BO) as the acceptor unit, along with a thiophene group as the π‐bridge between the donor and acceptor unit. For comparison, the copolymer composed of the 4,4‐diethylhexyl‐cyclopenta[2,1‐b :3,4‐b′ ]dithiophene (CPDT) donor unit and the BO acceptor unit has also been prepared. UV–vis spectra of the three copolymers display a panchromatic absorption ranging from 300 to 1100 nm. The optical band gap obtained from the Tauc relation for the CPDT‐containing polymer is 1.54 eV. With regard to the silole‐containing copolymers, the optical band gaps for nonfluorinated copolymer and fluorinated copolymer are reduced to 1.46 and 1.42 eV, respectively. In comparison with both nonfluorinated polymers, the photovoltaic performance of fluorinated polymer is significantly improved due to the increased J _sc and enhanced V _oc. Based on the indium tin oxide (ITO) coated glass/poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate)/polymer:phenyl‐C₆₁‐butyric acid methyl ester/LiF/Al device structure, the optimal device efficiency obtained from the fluorinated copolymer at room temperature under the illumination of AM 1.5 is 3.74%, with a high V _oc up to 0.87 V.

     

Simple Photochemical Route to Block Copolymers via Two‐Step Sequential Type II Photoinitiation

A simple method for the preparation of block copolymers by a two‐step sequential Type II photoinitiation is described. In the first step, amine functionalized poly(methyl methacrylate) (PMMA‐N(Et)₂) is prepared by photopolymerization of methyl methacrylate at λ = 350 nm using benzophenone and triethyl amine as photosensitizer and hydrogen donor, respectively. Subsequent benzophenone‐sensitized photopolymerization of tert‐butyl acrylate using PMMA‐N(Et)₂ as hydrogen donor yielded poly(methyl methacrylate)‐block‐poly(tert‐butyl acrylate). The obtained hydrophobic block copolymer is readily converted to amphiphilic polymer by hydrolysis of the tert‐butyl ester moieties of the block copolymer as demonstrated by contact angle measurements. All polymers are characterized by NMR, Fourier transform infrared and UV–vis spectroscopies, and differential scanning calorimetry (DSC) thermal analyses.     

Asymmetrically Substituted Poly(diitaconates) Obtained by Reversible Addition‐Fragmentation Chain Transfer (RAFT) Polymerization: Synthesis,Copolymerization Parameters,and Antimicrobial Activity

Asymmetrically substituted poly(diitaconate) copolymers are synthesized from 1‐((N‐tert‐butoxycarbonyl)‐2‐aminoethyl)‐4‐propyl diitaconate (PrIA) and different comonomers (N,N‐dimethyl‐acrylamide, DMAA; acrylic acid; or ((N‐tert‐butoxycarbonyl)‐2‐aminoethyl)methacrylate) by reversible addition–fragmentation chain transfer polymerization (RAFT). The RAFT copolymerization parameters of PrIA and DMAA are r_DMAA = 0.49 and r_PrIA = 0.17, compared to r_DMAA = 0.52 and r_PrIA = 0.54 obtained by free radical copolymerization (FRP). Thus, the RAFT process has a stronger trend to alternating polymerization than the FRP process. The polydispersity index of the RAFT copolymers is around 1.2–1.8, compared to 2.8–2.9 for the corresponding FRP copolymers. After removal of the tert‐butoxycarbonyl protective groups, antimicrobially active synthetic mimics of antimicrobial peptides are obtained. The thus activated poly(PrIA‐co‐DMAA) copolymers (repeat unit ratio 1:1) have an increasing activity against Escherichia coli and Staphylococcus aureus with increasing molar mass. The RAFT copolymers are slightly more active and less toxic than comparable FRP polymers, leading to a higher selectivity for bacteria over mammalian cells. Higher molar fractions of PrIA in poly(PrIA‐co‐DMAA) copolymers (up to 80 mol%) do not increase their antimicrobial activity; reduction of the BuIA content in poly(BuIA‐DMAA) (down to 10 mol%) leads to a loss of activity against both E. coli and S. aureus.     

Bis(4-monosubstituted-5(4H)oxazolinones) as coupling agents for block copolymer synthesis: reaction with hydroxy-terminated oligomers

The bulk chain-coupling reactions between hydroxy-terminated poly(oxytetramethylene), poly(oxyethylene), or poly(ε-caprolactone) and several bis(4-monosubstituted-5(4H)oxazolinones) were studied. The polyaddition reaction proceeds rapidly and without side reactions when a catalytic amount of Ti(OBu)₄ is used in the case of poly(oxytetramethylene) or poly(ε-caprolactone). On the other hand, the efficiency of the chain extension was much lower in the case of poly(oxyethylene). An explanation involving the coordination of poly(oxyethylene) oxygen atoms at the active sites of tetrabutoxytitanium is put forward. High molar mass block copolymers were synthesized by the chain-coupling reaction of mixtures of α,ω-dihydroxy-poly(oxytetramethylene) and -poly(ε-caprolactone) with bis(oxazolinones). The differential scanning calorimetry (DSC) study of the block copolymers revealed the existence of a microphase separation between the two blocks when the starting polymers have M _n ≥ 1000. For lower molar mass polymers amorphous products were obtained.     

Polyélectrolytes optiquement actifs à hydrophobie variable, 1. Copolymères amide-acide acryliques obtenus par hydrolyse contrǒlée des (±), (+) et (−) poly[N-(sec-butyl)-N-méthyl-acrylamides]

(±), (+), and (?) poly[N-(sec-butyl)-N-methyl-acrylamides] ( 1 ) are obtained by radical polymerization of (±), (?), and (+) N-(sec-butyl)-N-methyl-acrylamides (AAM). By gradual hydrolysis in CH₃COOH-HCl a series of copolymers was obtained ( 2 ); they are constituted by statistically distributed hydrophobic units derived from AAM and hydrophilic units derived from acrylic acid (AA) in different ratios as a function of the hydrolysis reaction time. Viscosity, optical rotation in methanol, solubility in various solvents, IR spectra from films and optical rotatory dispersion (ORD) have been studied as a function of the degree of conversion (τ). In order to explain the dependence of ORD and IR spectra on τ, the amid-acid hydrogen bonds were removed by methylation of COOH with diazomethane. During the neutralization of the different copolymers 2 by KOH, the increase in the ratio hydrophobic units/hydrophilic units strongly modifies the ionization behaviour of the COOH groups carried by the acrylic acid units.     

Amino acid based bioanalogous polymers. Synthesis of novel poly(urethane amide)s based on N,N′-(trimethylenedioxydicarbonyl)bis(phenylalanine)

The feasibility of synthesizing high-molecular-weight amino acid based bioanalogous polymers (AABBPs)-poly(urethane amide)s (PUA) — via polycondensation (PC) of di-p-nitrophenyl ester of N,N′-(trimethylenedioxydicarbonyl)bis(L-phenylalanine) ( 3 ) with diamines or their derivatives under mild conditions in organic solvents was studied for the first time. A regular PUA (η_red = 1,53 dL/g) was obtained by PC of 3 with hexamethylenediamine. A dipeptide (Phe-Phe) containing regular poly(ester urethane amide) (η_red = 0,58 dL/g) was synthesized by PC of 3 with p-toluenesulfonic acid salt of bis(L-phenylalanine) 1,4-butylene diester. A tripeptide (Phe-Lys-Phe) containing PUA (η_red = 0,38 dL/g) with pendent ester groups was prepared via PC of 3 with N,N-bis(trimethylsilyl)-L-lysine methyl ester. These novel AABBPs which may be considered as structural analogs of AB type bioanalogous polymers — conventional poly(amino acids) are of interest in enzymology, immunology, pharmacology, and biotechnology (as materials for biomedical applications).     

Pharmacologically active polymers, 17. Syntheses and characterization of polymeric derivatives of the antitumor agent methotrexate

Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid ( 1a ), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole-%) of substituted repeating units were prepared by polymer-analogous amidation and transesterification of the dimethyl ester of 1a and with N-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross-linking to divinyl ether-maleic anhydride (DIVEMA) copolymers of various molecular weights. This copolymer appeared to be of particular interest as carrier because of its established antitumor and immune-stimulating activity.—With the exception of the poly(vinyl alcohol) derivative, all polymers containing the 1a residue are water soluble at the physiological pH range. Besides the dimethyl ester of 1a used as convenient starting material for polymer-analogous reactions, further dialkyl esters of 1a were synthesized as low molecular weight model compounds for the study of the pharmacodynamic properties of polymers, substituted with 1a . The polymeric derivatives of 1a were purified by membrane filtration, solvent extraction, and reprecipitation; the polymers and the dialkylesters 1b–d were characterized by thin-layer chromatography, IR, NMR, UV and mass spectra, and elemental analysis. Preliminary results of the pharmacological studies with the DIVEMA derivatives of 1a are also reported.     

Untersuchungen zur Reaktionsfähigkeit statistisch verteilter Estergruppierungen in Copolymeren aus Styrol und Acrylsäureestern

The aminolysis of the ortho- and para-nitrophenyl esters of propanoic acid, isobutyric acid, 4-phenylbutanoic acid and 4-phenylpentanoic acid and of the copolymers of styrene and small amounts of acrylic acid was investigated with butylamine in dioxane. With a large excess of amine the esters with low molar mass obey first order kinetics. Addition of polystyrene shows no influence on the reaction rate. However, the copolymers showing a lower rate, react much slower and do not follow the first order rate law, though the initial reaction rate is proportional to the total concentration of the ester groups. The copolymers show nearly the same activation energies as the model esters with a low molar mass, and also the reaction rate exhibits a linear dependence on the concentration of amine. For these results two different explanations are discussed.     

Zirconocene-MAO-catalyzed homo- and copolymerizations of linear asymmetrically substituted dienes with propene: A novel strategy to functional (co)poly(α-olefin)s

The polymerization behavior of three linear asymmetrically substituted dienes, i.e. 6-phenyl-1,5-hexadiene ( A ), 7-methyl-1,6-octadiene ( B ) and R(+)-5,7-dimethyl-1,6-octadiene (isocitronellene, C ) is reported in order to study the effect of substitution at one vinylic group. Homopolymerization of these monomers with the catalyst system rac-Et[Ind]₂ZrCl₂/MAO resulted in no reaction products in the case of monomer A and in polymers with M _w = 3.5 kg/mol and M _w = 14.0 kg/mol with the monomers B and C , respectively. According to NMR analysis, the vinylene end group of isocitronellene remained untouched during polymerization, which excludes the possibility of cyclopolymerization or crosslinking. Copolymerization of isocitronellene with propene resulted in incorporation of the diene (15.6 mol-%) equal to the stoichiometric ratio in the monomer feed, with a relatively high catalyst activity. The degree of incorporated isocitronellene is inversely related to the polymerization temperature, providing control over crystallinity (isotacticity) and molecular weight of the copolymer. The isocitronellene homo- and copolymers could be epoxidized quantitatively and brominated to an extent of 90%. Perfluorohexyl iodide was grafted onto the isocitronellene/propene copolymer by radical reaction (conversion 80%), yielding a poly(α-olefin) with fluorinated side chains.     

Design and Photonic Properties of Novel Fluorinated Copolymers Bearing Phthalocyanine Side Groups

The design and characterization of amorphous alternating copolymers endowed with a satisfactory thermal stability are reported. These alternating poly(CTFE‐alt‐CEVE) copolymers are synthesized by radical copolymerization of chlorotrifluoroethylene (CTFE) with 2‐chloroethyl vinyl ether (CEVE), which are first modified into poly[CTFE‐alt‐(2‐iodoethyl vinyl ether)] copolymers and then azidated in high yields. Alkynyl CF₃‐containing phthalocyanines (Pcs) are then grafted via a copper‐catalyzed Huisgen dipolar 1,3‐addition (“grafting onto”), hence providing fluorinated copolymers with different degrees of grafting (from 10 to 72%) of Pc dangling groups. Electronic spectral (absorption, excitation, and fluorescence) and photophysical properties (fluorescence lifetimes, τ_F, and quantum yields, Φ_F) are evaluated.