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1.
PLoS One ; 13(11): e0206436, 2018.
Article in English | MEDLINE | ID: mdl-30475828

ABSTRACT

Cystectomy is the removal of all or part of the urinary bladder. It has been observed that there is significant regrowth of the bladder after partial cystectomy and this has been proposed to be through regeneration of the organ. Regrowth of tissue in mammals has been proposed to involve compensatory mechanisms that share many characteristics of true regeneration, like the growth of specialized structures such as blood vessels or nerves. However, the overall structure of the normal organ is not achieved. Here we tested if bladder growth after subtotal cystectomy (STC, removal of 50% of the bladder) was compensatory or regenerative. To do this we subjected adult female mouse bladders to STC and assessed regrowth using several established cellular parameters including histological, gene expression, cytokine accumulation and cell proliferation studies. Bladder function was analyzed using cystometry and the voiding stain on paper (VSOP) technique. We found that STC bladders were able to increase their ability to hold urine with the majority of volume restoration occurring within the first two weeks. Regenerating bladders had thinner walls with less mean muscle thickness, and they showed increased collagen deposition at the incision as well as throughout the bladder wall suggesting that fibrosis was occurring. Cell populations differed in their response to injury with urothelial regeneration complete by day 7, but stromal and detrusor muscle still incomplete after 8wks. Cells incorporated EdU when administered at the time of surgery and tracing of EdU positive cells over time indicated that many newborn cells originate at the incision and move mediolaterally. Basal urothelial cells and bladder mesenchymal stem cells but not smooth muscle cells significantly incorporated EdU after STC. Since anti-inflammatory cytokines play a role in regeneration, we analyzed expressed cytokines and found that no anti-inflammatory cytokines were present in the bladder 1wk after STC. Our findings suggest that bladder regrowth after cystectomy is compensatory and functions to increase the volume that the bladder can hold. This finding sets the stage for understanding how the bladder responds to cystectomy and how this can be improved in patients after suffering bladder injury.


Subject(s)
Cystectomy , Regeneration , Urinary Bladder/physiology , Urinary Bladder/surgery , Animals , Cicatrix/etiology , Cicatrix/genetics , Collagen/metabolism , Cystectomy/adverse effects , Cytokines/metabolism , Female , Fibrosis , Gene Expression Regulation , Mice , Recovery of Function , Urinary Bladder/metabolism , Urinary Bladder/pathology
2.
Front Pediatr ; 5: 132, 2017.
Article in English | MEDLINE | ID: mdl-28638819

ABSTRACT

Lower urinary tract symptoms secondary to posterior urethral valves (PUV) arise in boys during adolescence. The reasons for this have previously been attributed to increased urine output as boys experience increased growth. Additionally, there are few choices for clinicians to effectively treat these complications. We formed the new hypothesis that increased androgen levels at this time of childhood development could play a role at the cellular level in obstructed bladders. To test this hypothesis, we investigated the role of testosterone on bladder detrusor muscle following injury from partial bladder outlet obstruction (PO) in mice. A PO model was surgically created in juvenile male mice. A group of mice were castrated by bilateral orchiectomy at time of obstruction (CPO). Testosterone cypionate was administered to a group of castrated, obstructed mice (CPOT). Bladder function was assessed by voiding stain on paper (VSOP). Bladders were analyzed at 7 and 28 days by weight and histology. Detrusor collagen to smooth muscle ratio (Col/SM) was calculated using Masson's trichrome stain. All obstructed groups had lower max voided volumes (MVV) than sham mice at 1 day. Hormonally intact mice (PO) continued to have lower MVV at 7 and 28 days while CPO mice improved to sham levels at both time points. In accordance, PO mice had higher bladder-to-body weight ratios than CPO and sham mice demonstrating greater bladder hypertrophy. Histologically, Col/SM was lower in sham and CPO mice. When testosterone was restored in CPOT mice, MVV remained low at 7 and 28 days compared to CPO and bladder-to-body weight ratios were also greater than CPO. Histologic changes were also seen in CPOT mice with higher Col/SM than sham and CPO mice. In conclusion, our findings support a role for testosterone in the fibrotic changes that occur after obstruction in male mice. This suggests that while other changes may occur in adolescent boys that cause complication in boys with PUV, the bladder itself responds to testosterone at the cellular level. This opens the door to a new understanding of pathways that influence bladder fibrosis and could lead to novel approaches to treat boys with PUV.

3.
Pesqui. vet. bras ; 37(1): 1-7, jan. 2017. tab.
Article in Portuguese | LILACS, VETINDEX | ID: biblio-837442

ABSTRACT

Este estudo objetivou determinar a soroprevalência da Babesiose e Anaplasmose em bovinos dos municípios de Ouricuri e Petrolina, estado de Pernambuco, Brasil; e definir os possíveis fatores de risco para a ocorrência dessas doenças. Amostras de sangue foram coletadas para realização de teste sorológico por Imunofluorescência Indireta (RIFI). Questionários epidemiológicos sanitários foram aplicados aos produtores com o objetivo de identificar possíveis fatores de risco. Carrapatos foram coletados, identificados e testados por Reação em Cadeia da Polimerase (PCR) para o diagnóstico da infecção por Anaplasma marginale, Babesia bigemina e Babaesia bovis. O estudo foi conduzido com 861 bovinos, sendo 468 de Petrolina e 393 de Ouricuri. A soroprevalência de A. marginale, B. bigemina e B. bovis em Petrolina foi de 35,0% (164/468), 35,9% (168/468) e 32,3% (151/468), respectivamente; e em Ouricuri foi de 45,5% (179/393), 38,6% (152/393) e 54,9% (216/393), respectivamente. A co-infecção por Anaplasma spp. e Babesia spp. foi observada em 31,6% e 32,1% de amostras de Petrolina e Ouricuri, respectivamente. A detecção de DNA de Babesia spp. por PCR foi possível em 5,8% (8/137) carrapatos, dos quais em 62,5 % (5/8) foi detectada posteriormente infecção por B. bovis, e em 23,3% (32/137) por A. marginale. A presença de carrapatos, o uso de acaricidas, idade, raça, e o município de residência dos animais foram identificados como fatores de risco para TPB pela análise univariável e multivariável. Este estudo permitiu caracterizar os municípios estudados como de instabilidade enzoótica para esses hemoparasitos, e consequentemente, alertar para adoção de medidas adequadas de controle e realização de novos estudos.(AU)


This study aimed to determine the seroprevalence of Babesiosis and Anaplasmosis in cattle from the municipalities of Ouricuri and Petrolina, state of Pernambuco, Brazil, and to define the risk factors for the occurrence of the diseases. Blood samples were collected for serologic testing by Indirect Immunofluorescence Assay (IFA). Sanitary epidemiological questionnaires were applied to the producers aiming to identify possible risk factors. Ticks were collected, identified and tested by Polymerase Chain Reaction (PCR) for the diagnosis of infection by Anaplasma marginale, Babesia bigemina and Babesia bovis. The study was conducted with 861 cattle, being 468 in Petrolina and 393 in Ouricuri. The seroprevalence of A. marginale, B. bigemina and B. bovis in Petrolina was of 35.0% (164/468), 35.9% (168/468) and 32.3% (151/468), respectively; and in Ouricuri was 45.5% (179/393), 38.6% (152/393), and 54.9% (216/393), respectively. Co-infection for Anaplasma spp. and Babesia spp. was observed in 31.6% and 32.1% samples of Petrolina and Ouricuri, respectively. The detection of DNA of Babesia spp. by PCR was possible in 5.8% (8/137) ticks; which 62.5% (5/8) was detected later infection with B. bovis; and 23.3% (32/137) with A. marginale. The presence of ticks, the use of acaricide, age, race, and county of residence of the animals were identified as risk factors for TBD by univariate analysis and multivariate. This study allowed the characterization of the municipalities studied as enzootic instability areas for these hemoparasitic, and consequently alert for adoption of adequate control measures and new studies.(AU)


Subject(s)
Animals , Cattle , Anaplasmosis/blood , Anaplasmosis/epidemiology , Antibodies/analysis , Babesiosis/blood , Babesiosis/epidemiology , Seroepidemiologic Studies , Health Surveys
4.
Pesqui. vet. bras ; 37(1): 01-07, jan. 2017. tab
Article in Portuguese | LILACS, VETINDEX | ID: biblio-1487602

ABSTRACT

This study aimed to determine the seroprevalence of Babesiosis and Anaplasmosis in cattle from the municipalities of Ouricuri and Petrolina, state of Pernambuco, Brazil, and to define the risk factors for the occurrence of the diseases. Blood samples were collected for serologic testing by Indirect Immunofluorescence Assay (IFA). Sanitary epidemiological questionnaires were applied to the producers aiming to identify possible risk factors. Ticks were collected, identified and tested by Polymerase Chain Reaction (PCR) for the diagnosis of infection by Anaplasma marginale, Babesia bigemina and Babesia bovis. The study was conducted with 861 cattle, being 468 in Petrolina and 393 in Ouricuri. The seroprevalence of A. marginale, B. bigemina and B. bovis in Petrolina was of 35.0% (164/468), 35.9% (168/468) and 32.3% (151/468), respectively; and in Ouricuri was 45.5% (179/393), 38.6% (152/393), and 54.9% (216/393), respectively. Co-infection for Anaplasma spp. and Babesia spp. was observed in 31.6% and 32.1% samples of Petrolina and Ouricuri, respectively. The detection of DNA of Babesia spp. by PCR was possible in 5.8% (8/137) ticks; which 62.5% (5/8) was detected later infection with B. bovis; and 23.3% (32/137) with A. marginale. The presence of ticks, the use of acaricide, age, race, and county of residence of the animals were identified as risk factors for TBD by univariate analysis and multivariate. This study allowed the characterization of the municipalities studied as enzootic instability areas for these hemoparasitic, and consequently alert for adoption of adequate control measures and new studies.


Este estudo objetivou determinar a soroprevalência da Babesiose e Anaplasmose em bovinos dos municípios de Ouricuri e Petrolina, estado de Pernambuco, Brasil; e definir os possíveis fatores de risco para a ocorrência dessas doenças. Amostras de sangue foram coletadas para realização de teste sorológico por Imunofluorescência Indireta (RIFI). Questionários epidemiológicos sanitários foram aplicados aos produtores com o objetivo de identificar possíveis fatores de risco. Carrapatos foram coletados, identificados e testados por Reação em Cadeia da Polimerase (PCR) para o diagnóstico da infecção por Anaplasma marginale, Babesia bigemina e Babaesia bovis. O estudo foi conduzido com 861 bovinos, sendo 468 de Petrolina e 393 de Ouricuri. A soroprevalência de A. marginale, B. bigemina e B. bovis em Petrolina foi de 35,0% (164/468), 35,9% (168/468) e 32,3% (151/468), respectivamente; e em Ouricuri foi de 45,5% (179/393), 38,6% (152/393) e 54,9% (216/393), respectivamente. A co-infecção por Anaplasma spp. e Babesia spp. foi observada em 31,6% e 32,1% de amostras de Petrolina e Ouricuri, respectivamente. A detecção de DNA de Babesia spp. por PCR foi possível em 5,8% (8/137) carrapatos, dos quais em 62,5 % (5/8) foi detectada posteriormente infecção por B. bovis, e em 23,3% (32/137) por A. marginale. A presença de carrapatos, o uso de acaricidas, idade, raça, e o município de residência dos animais foram identificados como fatores de risco para TPB pela análise univariável e multivariável. Este estudo permitiu caracterizar os municípios estudados como de instabilidade enzoótica para esses hemoparasitos, e consequentemente, alertar para adoção de medidas adequadas de controle e realização de novos estudos.


Subject(s)
Animals , Cattle , Anaplasmosis/epidemiology , Anaplasmosis/blood , Antibodies/analysis , Babesiosis/epidemiology , Babesiosis/blood , Seroepidemiologic Studies , Health Surveys
5.
PLoS One ; 10(11): e0141437, 2015.
Article in English | MEDLINE | ID: mdl-26540309

ABSTRACT

Bladder fibrosis is an undesired end point of injury of obstruction and often renders the smooth muscle layer noncompliant. In many cases, the long-term effect of bladder fibrosis is renal failure. Despite our understanding of the progression of this disease, little is known about the cellular mechanisms that lead to a remodeled bladder wall. Resident stem (progenitor) cells have been identified in various organs such as the brain, heart and lung. These cells function normally during organ homeostasis, but become dysregulated after organ injury. Here, we aimed to characterize a mesenchymal progenitor cell population as a first step in understanding its role in bladder fibrosis. Using fluorescence activated cell sorting (FACS), we identified a Sca-1+/ CD34+/ lin- (PECAM-: CD45-: Ter119-) population in the adult murine bladder. These cells were localized to the stromal layer of the adult bladder and appeared by postnatal day 1. Cultured Sca-1+/ CD34+/ lin- bladder cells self-renewed, formed colonies and spontaneously differentiated into cells expressing smooth muscle genes. These cells differentiated into other mesenchymal lineages (chondrocytes, adipocytes and osteocytes) upon culture in induction medium. Both acute and partial obstruction of the bladder reduced expression of CD34 and changed localization of Sca-1 to the urothelium. Partial obstruction resulted in upregulation of fibrosis genes within the Sca-1+/CD34+/lin- population. Our data indicate a resident, mesenchymal stem cell population in the bladder that is altered by bladder obstruction. These findings provide new information about the cellular changes in the bladder that may be associated with bladder fibrosis.


Subject(s)
Mesenchymal Stem Cells/physiology , Urinary Bladder/cytology , Animals , Antigens, CD34/metabolism , Antigens, Ly/metabolism , Cell Lineage , Cells, Cultured , Fibrosis , Flow Cytometry , Fluorescent Antibody Technique , Membrane Proteins/metabolism , Mice , Polymerase Chain Reaction , Urinary Bladder/pathology , Urinary Bladder Neck Obstruction/pathology
6.
Pesqui. vet. bras ; 33(11): 1319-1324, Nov. 2013. ilus, tab
Article in English | LILACS | ID: lil-697877

ABSTRACT

To verify the occurrence of caseous lymphadenitis in sheep and goats on farms of Pernambuco, Brazil, and in animals slaughtered in two Brazilian cities (Petrolina/PE and Juazeiro/BA), and to characterize the susceptibility profile of Corynebacterium pseudotuberculosis to disinfectants and antimicrobials, and its relationship with biofilm production were the objectives of this study. 398 samples were tested for sensitivity to antimicrobial drugs, disinfectants, and biofilm production. Among the 108 samples collected on the properties, 75% were positive for C. pseudotuberculosis. Slaughterhouse samples indicated an occurrence of caseous lymphadenitis in 15.66% and 6.31% for animals slaughtered in Petrolina and Juazeiro respectively. With respect to antimicrobials, the sensitivity obtained was 100% for florfenicol and tetracycline; 99.25% for enrofloxacin, ciprofloxacin and lincomycin; 98.99% for cephalothin; 98.74% for norfloxacin and sulfazotrim; 97.74% for gentamicin; 94.22% for ampicillin; 91.71% for amoxicillin; 91.21% for penicillin G; 89.19% for neomycin and 0% for novobiocin. In analyzes with disinfectants, the efficiency for chlorhexidine was 100%, 97.20% for quaternary ammonium, 87.40% for chlorine and 84.40% for iodine. 75% of the isolates were weak or non-biofilm producers. For the consolidated biofilm, found that iodine decreased biofilm formation in 13 isolates and quaternary ammonia in 11 isolates. The reduction of the biofilm formation was observed for iodine and quaternary ammonium in consolidated biofilm formation in 33% and 28% of the isolates, respectively. The results of this study highlight the importance of establishing measures to prevent and control the disease.


Verificar a ocorrência de linfadenite caseosa de ovinos e caprinos em fazendas de Pernambuco, no Brasil e em animais abatidos em duas cidades brasileiras (Petrolina/PE e Juazeiro/BA), caracterizar o perfil de suscetibilidade de Corynebacgerium pseudotuberculosis a desinfetantes e a antimicrobianos e analisar sua relação com a produção de biofilme foram os objetivos deste estudo. 398 amostras foram testadas para a sensibilidade aos medicamentos antimicrobianos, desinfetantes e produção de biofilme. Entre as 108 amostras coletadas nas propriedades, 75% foram positivas para C. pseudotuberculosis. Amostras do matadouro indicaram a ocorrência de linfadenite caseosa em 15,66% e 6,31% para animais abatidos em Petrolina (PE) e Juazeiro (BA), respectivamente. Com relação aos antimicrobianos, a sensibilidade obtida foi de 100% para florfenicol e tetraciclina, 99,25% para a enrofloxacina, ciprofloxacina e lincomicina; 98,99% para cefalotina; 98,74% para norfloxacina e sulfazotrim; 97,74% para gentamicina; 94,22% para ampicilina, 91,71% para amoxicilina, 91,21% para a penicilina G, 89,19% para a neomicina e 0% para novobiocina. Nas análises com desinfetantes, a eficiência para a clorexidina foi de 100%, 97,20% para amônia quaternária, 87,40% para o cloro e 84,40% para o iodo. 75% dos isolados foram fracos produtores de biofilme. Para o biofilme consolidado, observou-se que o iodo diminuiu a formação de biofilme em 13 isolados e a amônia quaternária em 11 isolados. A redução da formação de biofilme foi observada no biofilme consolidado, para iodo e amônia quaternária, em 33% e 28% das amostras, respectivamente. Os resultados deste estudo destacam a importância de se estabelecer medidas para prevenir e controlar a doença.


Subject(s)
Animals , Biofilms , Goats/immunology , Corynebacterium pseudotuberculosis/pathogenicity , Lymphadenitis/veterinary , Sheep/immunology , Anti-Infective Agents/adverse effects , Disinfectants/adverse effects
7.
J Biomed Opt ; 15(5): 051604, 2010.
Article in English | MEDLINE | ID: mdl-21054078

ABSTRACT

Cardiolipin is a unique phospholipid of the mitochondrial inner membrane. Its peroxidation correlates with release of cytochrome c and induction of apoptosis. The phthalocyanine photosensitizer Pc 4 binds preferentially to the mitochondria and endoplasmic reticulum. Earlier Förster resonance energy transfer studies showed colocalization of Pc 4 and cardiolipin, which suggests cardiolipin as a target of photodynamic therapy (PDT) with Pc 4. Using liposomes as membrane models, we find that Pc 4 binds to cardiolipin-containing liposomes similarly to those that do not contain cardiolipin. Pc 4 binding is also studied in MCF-7c3 cells and those whose cardiolipin content was reduced by treatment with palmitate. Decreased levels of cardiolipin are quantified by thin-layer chromatography. The similar level of binding of Pc 4 to cells, irrespective of palmitate treatment, supports the lack of specificity of Pc 4 binding. Thus, factors other than cardiolipin are likely responsible for the preferential localization of Pc 4 in mitochondria. Nonetheless, cardiolipin within liposomes is readily oxidized by Pc 4 and light, yielding apparently mono- and dihydroperoxidized cardiolipin. If similar products result from exposure of cells to Pc 4-PDT, they could be part of the early events leading to apoptosis following Pc 4-PDT.


Subject(s)
Cardiolipins/chemistry , Cardiolipins/metabolism , Indoles/metabolism , Photosensitizing Agents/metabolism , Binding Sites , Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Cell Line, Tumor , Female , Fluorescence Resonance Energy Transfer , Humans , In Vitro Techniques , Liposomes , Membrane Potential, Mitochondrial , Mitochondrial Membranes/metabolism , Oxidation-Reduction , Palmitates/pharmacology , Photochemical Processes , Photochemotherapy
8.
Photochem Photobiol ; 85(5): 1189-200, 2009.
Article in English | MEDLINE | ID: mdl-19508642

ABSTRACT

The phthalocyanine photosensitizer Pc 4 has been shown to bind preferentially to mitochondrial and endoplasmic reticulum membranes. Upon photoirradiation of Pc 4-loaded cells, membrane components, especially Bcl-2, are photodamaged and apoptosis, as indicated by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase, is triggered. A series of analogs of Pc 4 were synthesized, and the results demonstrate that Pcs with the aminopropylsiloxy ligand of Pc 4 or a similar one on one side of the Pc ring and a second large axial ligand on the other side of the ring have unexpected properties, including enhanced cell uptake, greater monomerization resulting in greater intracellular fluorescence and three-fold higher affinity constants for liposomes. The hydroxyl-bearing axial ligands tend to reduce aggregation of the Pc and direct it to lysosomes, resulting in four to six times more killing of cells, as defined by loss of clonogenicity, than with Pc 4. Whereas Pc 4-PDT photodamages Bcl-2 and Bcl-xL, Pc 181-PDT causes much less photodamage to Bcl-2 over the same dose-response range relative to cell killing, with earlier cleavage of Bid and slower caspase-3-dependent apoptosis. Therefore, within this series of photosensitizers, these hydroxyl-bearing axial ligands are less aggregated than is Pc 4, tend to localize to lysosomes and are more effective in overall cell killing than is Pc 4, but induce apoptosis more slowly and by a modified pathway.


Subject(s)
Indoles/pharmacology , Lysosomes/drug effects , Mitochondria/drug effects , Photochemotherapy , Photosensitizing Agents/pharmacology , Silicon/chemistry , Isoindoles , Magnetic Resonance Spectroscopy
9.
J Am Chem Soc ; 128(14): 4792-801, 2006 Apr 12.
Article in English | MEDLINE | ID: mdl-16594716

ABSTRACT

Herein are reported the synthesis, structure, and electronic properties of a series of tertiary di- and polyarylureas possessing pyrene and nitrobenzene end groups separated by a variable number of internal phenylenediamine bridging groups. These molecules adopt folded "protophane" structures in which the adjacent arenes are loosely pi-stacked. The behavior of both the pyrene and nitrobenzene singlet states has been investigated by means of femtosecond broadband pump-probe spectroscopy, and the transients have been assigned on the basis of comparison to reference molecules. Femtosecond time resolution permits direct observation of the fast internal conversion process for both the pyrene and nitrobenzene upper singlet states, as well as the intersystem crossing of nitrobenzene. The ultrafast (ca. 100 fs) charge separation of the donor-acceptor urea having no bridging group is attributed to an internal conversion process. The slower charge separation and charge recombination of the donor-acceptor urea having a single bridging group occur via a bridge-mediated superexchange process. Addition of a second bridging unit results in a role reversal for the pyrene singlet state, which now serves as an excited-state acceptor with the bridging units serving as the electron donors. The change in the directionality of electron transfer upon addition of a second bridging phenylenediamine is a consequence of a decrease in the bridge oxidation potential as well as a decrease in the rate constant for single-step superexchange electron transfer.

10.
J Org Chem ; 70(8): 2974-9, 2005 Apr 15.
Article in English | MEDLINE | ID: mdl-15822956

ABSTRACT

A convergent approach has been developed for the preparation of nonsymmetric tertiary arylureas possessing two or three urea linkages. This approach has been used for the preparation of ureas possessing 1-naphthylenyl and 4-nitrophenyl end groups separated by either one or two phenylene diamine bridging units. These ureas were constructed as prototypes for donor-bridge-acceptor systems based on tertiary arylurea architecture. AM1 calculations indicate a preference of these arylureas for folded, protophane structures in which the aryl groups are loosely pi-stacked. Analysis of the (1)H NMR chemical shifts supports the assignment of folded structures in solution. The absorption and luminescence spectra of tertiary ureas possessing 1-naphthylenyl and/or 4-nitrophenyl are reported. The absence of fluorescence and appearance of structured phosphorescence at 77 K are attributed to nitrophenyl-localized lowest energy singlet and triplet states. Localization of excitation on the acceptor chromophore precludes investigation of charge transfer in these systems.


Subject(s)
Chemistry, Pharmaceutical/methods , Urea/chemistry , Indicators and Reagents , Magnetic Resonance Spectroscopy , Molecular Conformation , Molecular Structure
11.
J Phys Chem A ; 109(36): 8106-12, 2005 Sep 15.
Article in English | MEDLINE | ID: mdl-16834196

ABSTRACT

The synthesis, structure, and spectroscopy of a family of tertiary di- and polyarylureas possessing a naphthyl and several different arene end groups separated by a variable number of internal phenylenediamine linking groups are reported. Molecular modeling and (1)H NMR chemical shift data are consistent with the formation of compact, folded structures in which the arene groups adopt a splayed face-to-face geometry. The structure and solvent dependence of the electronic absorption and emission spectra have been determined and are interpreted with the aid of ZINDO calculations. The electronic absorption spectra are relatively insensitive to the choice of arene end group, the number of linking groups, and the solvent polarity. In contrast, the solution fluorescence is highly dependent upon the structure and solvent polarity. These observations are attributed to a small change in polarity upon excitation of the ground state to a naphthalene-localized Franck-Condon singlet state, which can undergo relaxation to a highly polar emissive state with extensive charge-transfer character.


Subject(s)
Naphthols/chemistry , Urea/analogs & derivatives , Urea/chemistry , Electrochemistry , Electronics , Magnetic Resonance Spectroscopy , Models, Molecular , Spectrophotometry
12.
J Phys Chem B ; 109(11): 4893-9, 2005 Mar 24.
Article in English | MEDLINE | ID: mdl-16863144

ABSTRACT

The syntheses, structures, and spectroscopy of a series of oligomeric tertiary oligophenylureas possessing one to five phenyl rings are reported. A convergent synthetic method employing tertiary monoamine and diamine building blocks is employed. NMR and molecular modeling are indicative of folded structures for all of the oligophenylureas in which adjacent phenyl rings have a splayed face-to-face geometry. NMR chemical shifts, absorption and emission maxima, and electrochemical oxidation potentials are all dependent upon the number of phenyl rings. The addition of a first inner phenyl has a pronounced effect on the chemical shifts, while a second and third inner phenyl have diminished effects. The oxidation potentials of the oligophenylureas display an abrupt decrease upon the addition of the second inner phenyl. The absorption and emission spectra are relatively insensitive to the addition of one to three inner phenyl rings. The electronic structures of the oligophenylureas possessing one to eight rings have been analyzed using ZINDO calculations. The frontier orbitals of the ureas with one to three phenyl rings are localized on a single phenyl ring (the inner ring for the three-ring urea), whereas the frontier orbitals of the higher oligomers are delocalized over two phenyl rings. In all cases, urea-localized n,pi* transitions are lower in energy than the phenyl-localized pi,pi* transitions. The changes in properties with added phenyl rings parallel those previously observed for multilayered cyclophanes; however, they are less pronounced because of weaker coupling between the phenyl rings of the oligophenylureas.


Subject(s)
Phenylurea Compounds/chemistry , Magnetic Resonance Spectroscopy , Mass Spectrometry , Models, Molecular
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