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1.
Korean J Intern Med ; 36(5): 1074-1082, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32898394

RESUMO

BACKGROUND/AIMS: There are no definite guidelines for the management of gastric lesions diagnosed as indefinite for dysplasia (IND) by endoscopic forceps biopsy (EFB). Therefore, this study aimed to evaluate the clinical outcomes of gastric IND and predictive factors for gastric neoplasm. METHODS: This study included 457 patients with a first diagnosis of gastric IND by EFB between January 2005 and December 2013. Patient characteristics and endoscopic and pathological data were reviewed and compared. RESULTS: Of the 457 gastric IND patients, 128 (28%) were diagnosed with invasive carcinoma, 21 (4.6%) with high-grade dysplasia, 31 (6.8%) with low-grade dysplasia, and 277 (60.6%) as negative for dysplasia. Of lesions observed, 180 (39.4%) showed upgraded histology. Multivariate analysis revealed that surface erythema (odds ratio [OR], 2.804; 95% confidence interval [CI], 1.741 to 4.516), spontaneous bleeding (OR, 2.618; 95% CI, 1.298 to 5.279), lesion size ≥ 1 cm (OR, 5.762; 95% CI, 3.459 to 9.597), and depressed morphology (OR, 2.183; 95% CI, 1.155 to 4.124) were significant risk factors for high-grade dysplasia or adenocarcinoma. The ORs associated with 2 and ≥ 3 risk factors were 7.131 and 34.86, respectively. CONCLUSION: Precautions should be taken in the management of gastric IND patients, especially when risk factors, including surface erythema, spontaneous bleeding, lesion size ≥ 1 cm, and depressed morphology are present. Considering the combined effect of the presence of multiple risk factors on the incidence of high-grade dysplasia or adenocarcinoma, endoscopic resection should be recommended if a gastric IND patient has at two or more of these factors.


Assuntos
Adenocarcinoma , Lesões Pré-Cancerosas , Neoplasias Gástricas , Biópsia , Mucosa Gástrica , Gastroscopia , Humanos , Estudos Retrospectivos , Medição de Risco , Fatores de Risco
2.
Gastrointest Endosc ; 89(4): 825-831.e1, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30403966

RESUMO

BACKGROUND AND AIMS: EUS-guided fine-needle aspiration/biopsy (EUS-FNA/B) has a high diagnostic accuracy for pancreatic tumors. Most reports have focused on the diagnostic yield of cytology or histology; the ability of various FNA/B techniques to obtain an adequate mass of cells or tissue has rarely been investigated. METHODS: Patients with suspected pancreatic malignancy underwent EUS-FNB using a 22-gauge ProCore needle by either the stylet slow-pull-back technique (group A), conventional negative suction after stylet removal (group B), or non-suction after stylet removal (group C) in the absence of an on-site cytopathologist. The adequacy of the 3 techniques based on the diagnostic yield, cellularity, blood contamination, and core-tissue acquisition was evaluated. RESULTS: A total of 50 patients (27 males) were analyzed. The mean tumor size was 21 to 40 mm in 54%. The rate of a good or excellent proportion of cellularity was highest in group A compared with groups B and C (72% vs 60% vs 50%, P = .049). A >25% rate of blood contamination was more prevalent in group B (30% vs 42% vs 10%, P = .009). The rate of adequate core-tissue acquisition was not different (52% vs 34% vs 50%, P = .140). Based on the multivariate generalized estimation equation, the stylet slow-pull-back technique and a tumor size >40 mm were favorable factors for diagnostic adequacy. CONCLUSIONS: The stylet slow-pull-back technique might enable acquisition of tissue and assessment of cellularity for the diagnosis of pancreatic tumors suspected to be malignant. (Clinical trial registration number: KCT0002190.).


Assuntos
Aspiração por Agulha Fina Guiada por Ultrassom Endoscópico/métodos , Tumores Neuroendócrinos/patologia , Neoplasias Intraductais Pancreáticas/patologia , Neoplasias Pancreáticas/patologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Tumores Neuroendócrinos/diagnóstico , Neoplasias Intraductais Pancreáticas/diagnóstico , Neoplasias Pancreáticas/diagnóstico , Carga Tumoral
3.
Dig Dis Sci ; 64(1): 144-151, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30054843

RESUMO

BACKGROUND AND STUDY AIM: Although propofol is widely used for sedation for endoscopic procedures, concerns remain regarding cardiopulmonary adverse events. Etomidate has little effect on the cardiovascular and respiratory systems, but patient satisfaction analysis is lacking. We compared the efficacy and safety of balanced propofol and etomidate sedation during advanced endoscopic procedures. METHODS: As a randomized noninferiority trial, balanced endoscopic sedation was achieved using midazolam and fentanyl, and patients were randomly assigned to receive propofol (BPS) or etomidate (BES) as add-on drug. The main outcomes were sedation efficacy measured on a 10-point visual analog scale (VAS) and safety. RESULTS: In total, 186 patients (94 in the BPS group and 92 in the BES group) were evaluated. BES did not show noninferiority in terms of overall patient satisfaction, with a difference in VAS score of -0.35 (97.5 % confidence interval -1.03 to ∞, p = 0.03). Among endoscopists and nurses, BES showed noninferiority to BPS, with differences in VAS scores of 0.06 and 0.08, respectively. Incidence of cardiopulmonary adverse events was lower in the BES group (27.7 versus 14.1 %, p = 0.023). Hypoxia occurred in 5.3 and 1.1 % of patients in the BPS and BES group (p = 0.211). Myoclonus occurred in 12.1 % (11/92) in the BES group. BES had lower risk of overall cardiopulmonary adverse events (odds ratio 0.401, p = 0.018). CONCLUSIONS: BES was not noninferior to BPS in terms of patient satisfaction. However, BES showed better safety outcomes in terms of cardiopulmonary adverse events.


Assuntos
Sedação Consciente/métodos , Estado de Consciência/efeitos dos fármacos , Endoscopia do Sistema Digestório/métodos , Etomidato/administração & dosagem , Hipnóticos e Sedativos/administração & dosagem , Propofol/administração & dosagem , Idoso , Colangiopancreatografia Retrógrada Endoscópica , Colonoscopia , Sedação Consciente/efeitos adversos , Método Duplo-Cego , Quimioterapia Combinada , Ressecção Endoscópica de Mucosa/efeitos adversos , Endoscopia do Sistema Digestório/efeitos adversos , Etomidato/efeitos adversos , Feminino , Fentanila/administração & dosagem , Gastroscopia , Humanos , Hipnóticos e Sedativos/efeitos adversos , Masculino , Midazolam/administração & dosagem , Pessoa de Meia-Idade , Satisfação do Paciente , Propofol/efeitos adversos , República da Coreia , Resultado do Tratamento
4.
Gut Liver ; 12(5): 597-605, 2018 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-29730907

RESUMO

Background/Aims: Needle-knife precut fistulotomy (NK-F) is a well-known freehand technique for difficult biliary cannulation (DBC). Another approach involves the use of Iso-Tome®, a modified precutting device with an insulated needle tip to prevent direct thermal injury. This comparative study aimed to evaluate the efficacy of the Iso-Tome® precut (IT-P) compared to that of NK-F for DBC. Methods: Patients with a naïve papilla who underwent early IT-P or NK-F for DBC were enrolled. DBC was defined as failure to achieve selective biliary access by wire-guided cannulation despite 5 minutes of attempted cannulation, ≥5 papillary contacts, or a hooknose-shaped papilla. The primary endpoint was the primary technical success rate, which was based on a noninferiority model. Results: A total of 239 DBC cases were enrolled. The primary technical success rates were 74.7% (89/119) in the IT-P group and 91.6% (110/120) in the NK-F group (lower limit of 90% confidence interval, -0.23; p=0.927 for a noninferiority margin of 10%). The total technical success rates were 87.4% and 95.0%, respectively (p=0.038). The mean precutting times for successful biliary access were 11.2 minutes for IT-P and 7.3 minutes for NK-F (p<0.01). The procedure-related adverse event rates were 9.2% for IT-P and 5.8% for NK-F (p=0.318). The rates of post-endoscopic retrograde cholangiopancreatography pancreatitis were 4.2% and 2.5%, respectively (p=0.499). Conclusions: IT-P failed to exhibit noninferiority compared with NK-F regarding the primary technical success rate of DBC, but there was no difference in the frequency of adverse events.


Assuntos
Ampola Hepatopancreática/cirurgia , Cateterismo/instrumentação , Colangiopancreatografia Retrógrada Endoscópica/instrumentação , Esfinterotomia Endoscópica/instrumentação , Instrumentos Cirúrgicos , Idoso , Cateterismo/métodos , Colangiopancreatografia Retrógrada Endoscópica/métodos , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Agulhas , Estudos Prospectivos , Esfinterotomia Endoscópica/métodos , Resultado do Tratamento
5.
Dig Dis Sci ; 63(3): 775-780, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29383606

RESUMO

BACKGROUND/AIMS: Submucosal injection with indigo carmine mixed solution can improve the delineation of colorectal neoplasia during endoscopic mucosal resection (EMR). Thus, the aim of this study was to evaluate the efficacy of submucosal injection with indigo carmine mixed solution during EMR of colorectal neoplasia. METHODS: This was a prospective, randomized, controlled study of a total of 212 neoplastic colon polyps (5-20 mm) subjected to EMR in a single tertiary university hospital. The patients were randomized into two groups according to whether or not indigo carmine mixed solution was used, and the complete resection rate (CRR) after EMR was evaluated. RESULTS: A total of 212 neoplastic polyps (normal saline group, 115; indigo carmine group, 97) were successfully removed by EMR. There was no significant difference in the CRR (92.8 vs. 89.6%, p = 0.414) or macroscopic delineation (86.0 vs. 93.8%, p = 0.118) between the two groups. In a separate analysis of sessile serrated adenomas/polyps (SSAs/Ps), macroscopic delineation was better in the indigo carmine group than the normal saline group (87.5 vs. 53.8%), albeit not significantly (p = 0.103). In univariate analyses, the CRR was significantly related to polyp location, polyp morphology, macroscopic delineation, and pathologic findings. In a multiple logistic regression analysis, macroscopic delineation (odds ratio (OR), 7.616, p = 0.001) and polyp pathology (OR, 8.621; p < 0.001) were significantly associated with the CRR. CONCLUSIONS: Submucosal injection with indigo carmine mixed solution did not improve the CRR or macroscopic delineation of EMR of colorectal neoplasias.


Assuntos
Pólipos do Colo/patologia , Pólipos do Colo/cirurgia , Corantes/administração & dosagem , Ressecção Endoscópica de Mucosa/métodos , Índigo Carmim/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Injeções , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento
6.
Scand J Gastroenterol ; 53(12): 1541-1546, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30600737

RESUMO

BACKGROUND: The factors associated with recurrence of colonic neoplasm after endoscopic resection with a positive lateral margin are not well known. Thus, we evaluate the relationship between recurrence and positive lateral margin after endoscopic en bloc resection of colorectal neoplasm. METHODS: A retrospective review of 9302 patients who underwent colonic endoscopic resection from January 2008 to January 2015. Of these, a total of 76 patients with positive lateral margins with clear evidence of the its location on endoscopic picture after endoscopic en bloc resection of colorectal neoplasm (>10 mm) were included. RESULTS: Ten of 76 (13.2%) patients experienced recurrence during the follow-up period (mean f/u month, 21.7 ± 15.6). In cases with positive lateral margins, the 3- and 5-year local recurrence rate of colorectal neoplasm was 28.1% and 40.1%, respectively. The histological features of the recurrence group were as follows: one case of adenocarcinoma [from low-grade adenoma (LGA)]; two cases of high-grade adenoma (HGA) (one from HGA and one from LGA); and seven cases of LGA (four from adenocarcinoma, two from LGA, and one from HGA). The mean age of patients, locations of the lesions, and histologic type were not significantly associated with local recurrence. In multivariate Poisson regression analyses, total length of lateral margin involvement ≥8 mm (relative risk 12.51; 95% CI 1.11-140.34, p = .040) was a significant predictor of local recurrence. CONCLUSIONS: Positive lateral margins ≥8 mm may be a reliable predictor of local recurrence after endoscopic en bloc resection of colorectal neoplasm.


Assuntos
Adenocarcinoma/cirurgia , Adenoma/cirurgia , Colectomia/métodos , Neoplasias Colorretais/cirurgia , Laparoscopia/métodos , Recidiva Local de Neoplasia/diagnóstico , Adenocarcinoma/patologia , Adenoma/patologia , Idoso , Neoplasias Colorretais/patologia , Dissecação/métodos , Feminino , Seguimentos , Humanos , Estimativa de Kaplan-Meier , Masculino , Margens de Excisão , Pessoa de Meia-Idade , Análise Multivariada , Curva ROC , Análise de Regressão , República da Coreia , Estudos Retrospectivos , Resultado do Tratamento
7.
Dig Endosc ; 29(3): 369-376, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28181706

RESUMO

BACKGROUND AND AIM: As society ages, the need for endoscopic retrograde cholangiopancreatography (ERCP) is increasing. This prospective comparative study evaluated the safety and efficacy of midazolam- versus propofol-based sedations by non-anesthesiologists during therapeutic ERCP in patients over 80 years of age. METHODS: A total of 100 patients over 80 years of age who required therapeutic ERCP were enrolled and randomly received midazolam + fentanyl (MF group) or propofol + fentanyl (PF group) sedation. Endoscopic sedation was titrated to a moderate level and carried out by trained registered nurses. Main outcome measurements were sedation safety in terms of cardiopulmonary components and efficacy measured on a 10-point visual analogue scale (VAS). RESULTS: Regarding safety, hypoxia occurred in seven (14%) in the MF group and in eight patients (16%) in the PF group (P = 0.779). Increased O2 supply was more frequent in the PF group (32% vs 42%), albeit not significantly so. There were no differences in the frequency of hypotension, bradycardia or tachycardia between the two groups. Mean VAS score for overall satisfaction with sedation by patients, endoscopists, and nurses and the scores for pain during the procedures were not different between the two groups. There was no significant difference in the procedure outcomes or rate of ERCP-related complications. CONCLUSIONS: There were no significant differences of safety and efficacy between midazolam- and propofol-based sedation in patients over 80 years of age. Increased O2 supply was more frequent in the propofol group, but the prevalence of hypoxia did not differ significantly.


Assuntos
Doenças Biliares/terapia , Colangiopancreatografia Retrógrada Endoscópica/métodos , Sedação Consciente/métodos , Midazolam/administração & dosagem , Pancreatopatias/terapia , Propofol/administração & dosagem , Idoso de 80 Anos ou mais , Relação Dose-Resposta a Droga , Feminino , Humanos , Hipnóticos e Sedativos/administração & dosagem , Injeções Intravenosas , Masculino , Dor/prevenção & controle , Medição da Dor , Estudos Prospectivos , Resultado do Tratamento
8.
Sci Rep ; 6: 36581, 2016 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-27811954

RESUMO

The thermoelectric properties of sub-stoichiometric TiO2-x deposits produced by cascaded-plasma spray process are investigated from room-temperature to 750 K. Sub-stoichiometric TiO2-x deposits are formed through in-situ reaction of the TiO1.9 within the high temperature plasma flame and manipulated through introduction of varying amounts of hydrogen in the plasma. Although the TiO2-x particles experience reduction within plasma, it can also re-oxidize through interaction with the surrounding ambient atmosphere, resulting in a complex interplay between process conditions and stoichiometry. The deposits predominantly contain rutile phase with presence of Magneli phases especially under significantly reducing plasma conditions. The resultant deposits show sensitivity to thermoelectric properties and under certain optimal conditions repeatedly show Seebeck coefficients reaching values of -230 µV K-1 at temperatures of 750 K while providing an electrical conductivity of 5.48 × 103 S m-1, relatively low thermal conductivity in the range of 1.5 to 2 W m-1 K-1 resulting in power factor of 2.9 µW cm-1 K-2. The resultant maximum thermoelectric figure of merit value reached 0.132 under these optimal conditions. The results point to a potential pathway for a large-scale fabrication of low-cost oxide based thermoelectric with potential applicability at moderate to high temperatures.

9.
Dig Dis Sci ; 61(7): 2094-101, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26873537

RESUMO

BACKGROUND/AIMS: Concern regarding the safety and efficacy of therapeutic endoscopic retrograde cholangiopancreatography (ERCP) in elderly patients is increasing as a result of the aging society. However, there are limited data, especially in the super-aged elderly. This study aimed to evaluate the efficacy and safety of therapeutic ERCP in patients ≥80 years of age. METHODS: Patients 80 years of age or older (n = 312) and younger than 65 years (n = 312) who underwent therapeutic ERCP from June 2006 to April 2014 were randomly selected and analyzed retrospectively. The main outcome measurements were therapeutic ERCP-related complications and clinical outcomes in the two groups. RESULTS: Choledocholithiasis combined with gallbladder stone was the most common indication for ERCP in both groups. Comorbid diseases (70.5 and 29.8 %, p < 0.001) and the use of anti-thrombotic drugs (18.6 and 1.6 %, p < 0.001) were more frequent in the super-aged group. The mean procedure time was longer, and the frequency of second ERCP was more common in the super-aged group. However, the technical success rate (94.9 and 97.4 %, p = 0.096) and the procedure-related complication rate (4.8 and 5.8 %, p = 0.592) were not different between the two groups. Post-ERCP pancreatitis occurred in 1.3 % of the super-aged group and in 2.9 % of the control group (p = 0.262). Cardiopulmonary complications occurred in 1.9 % of patients in each group (p = 1.0). CONCLUSIONS: Therapeutic ERCP is comparable in terms of efficacy and safety between patients ≥80 years and those <65 years of age, although the elderly group had a higher rate of comorbid diseases and used anti-thrombotic drugs more frequently.


Assuntos
Colangiopancreatografia Retrógrada Endoscópica/efeitos adversos , Colangiopancreatografia Retrógrada Endoscópica/métodos , Idoso de 80 Anos ou mais , Colecistite/terapia , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pancreatopatias/terapia , Estudos Retrospectivos
11.
Tuberc Respir Dis (Seoul) ; 78(1): 23-6, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25653693

RESUMO

Metastatic squamous cell carcinoma from a cancer of unknown primary (CUP) affecting the intrathoracic lymph node is very rare. We reported a case of metastatic squamous cell carcinoma in the hilar and interlobar lymph node from a patient with CUP and reviewed the associated literature. Abnormal mass in the right hilar area was incidentally detected. A chest computed tomography scan showed a 2.5-cm diameter mass in the right hilum that had changed little in size for 3 years. The patient underwent a right pneumonectomy and mediastinal lymph node dissection. A metastatic squamous cell carcinoma in the hilar and interlobar lymph nodes without a primary lung or other lesion was diagnosed. The patient received adjuvant chemotherapy for a diagnosis of T0N1M0 lung cancer.

12.
Nat Commun ; 4: 1347, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23299897

RESUMO

Although high-temperature superconductor cuprates have been discovered for more than 25 years, superconductors for high-field application are still based on low-temperature superconductors, such as Nb(3)Sn. The high anisotropies, brittle textures and high manufacturing costs limit the applicability of the cuprates. Here we demonstrate that the iron superconductors, without most of the drawbacks of the cuprates, have a superior high-field performance over low-temperature superconductors at 4.2 K. With a CeO(2) buffer, critical current densities >10(6) A cm(-2) were observed in iron-chalcogenide FeSe(0.5)Te(0.5) films grown on single-crystalline and coated conductor substrates. These films are capable of carrying critical current densities exceeding 10(5) A cm(-2) under 30 tesla magnetic fields, which are much higher than those of low-temperature superconductors. High critical current densities, low magnetic field anisotropies and relatively strong grain coupling make iron-chalcogenide-coated conductors particularly attractive for high-field applications at liquid helium temperatures.

15.
Chem Commun (Camb) ; 46(10): 1679-81, 2010 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-20177614

RESUMO

A carbonyl group was positioned between 1,8-naphthalimide and di-2-picolylamine (DPA) and played a key role of displaying fluorescence enhancements with heavy and transition metal (HTM) ions through increasing the oxidation potential of the fluorophore, blocking HTM ions from sterically interacting with the naphthalimide fluorophore, and by acting as a sacrificial donor.


Assuntos
Corantes Fluorescentes/química , Corantes Fluorescentes/síntese química , Metais Pesados/química , Elementos de Transição/química , Desenho de Fármacos , Transporte de Elétrons , Naftalimidas/química , Espectrometria de Fluorescência , Água/química
16.
Org Lett ; 12(6): 1272-5, 2010 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-20158262

RESUMO

A novel boron complex bearing a pyrene ligand (CPB) was synthesized and introduced as the first example of a binuclear boron complex in organic light-emitting diodes. In the solid state, CPB2 exhibited strong red emission. In the devices, red emission with Commission International de L'Eclairage (CIE) coordinates of (0.57, 0.42) was obtained by tuning the weight concentration of CPB2. CPB2 behaved as both an emitting and electron transporting material.


Assuntos
Compostos de Boro/síntese química , Elétrons , Luz , Pirenos/química , Compostos de Boro/química , Eletroquímica , Ligantes , Medições Luminescentes , Modelos Moleculares , Estrutura Molecular , Espectrometria de Fluorescência , Estereoisomerismo
17.
Inorg Chem ; 48(21): 10455-65, 2009 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-19780527

RESUMO

Salen-type ligands comprised of ethylenediamine or 1,2-cyclohexenediamine, along with an salicylaldehyde bearing a methyl substituent on its 3-position and a -[CR(CH(2)CH(2)CH(2)N(+)Bu(3))(2)] (R = H or Me) on its 5-position, unexpectedly afford cobalt(III) complexes with uncoordinated imines. In these complexes, two salen-phenoxys and two 2,4-dinitrophenolates (DNPs), which counter the quaternary ammonium cations, coordinate persistently with cobalt, while two other DNPs are fluxional between a coordinated and an uncoordinated state in THF at room temperature. The complexes of this binding mode show excellent activities in carbon dioxide/propylene oxide copolymerization (TOF, 8300-13,000 h(-1)) but with some fluctuation in induction times (1-10 h), depending on how dry the system is. The induction time is shortened (<1.0 h) and activity is increased approximately 1.5 times upon the replacement of the two fluxional DNPs with 2,4-dinitrophenol-2,4-dinitrophenolate homoconjugation ([DNP...H...DNP](-)). Imposing steric congestion either by replacing the methyl substituent on the salicylaldehyde with tert-butyl or by employing H(2)NCMe(2)CMe(2)NH(2) instead of ethylenediamine or 1,2-cyclohexenediamine results in conventional imine-coordinating complexes, which show lower activities than uncoordinated imine complexes.

18.
Inorg Chem ; 47(13): 5666-76, 2008 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-18543905

RESUMO

Color-tunable Zn(II) complexes of the type Zn( N,O-OPh (OxZ)ArX) 2 ( 5), where the ligand consists of an oxazolylphenolate ion connected at the 4-position by a 2,4-substituted aryl functional group with X = NMe 2 a, OMe b, Ph c, Cl d, F 2 e, and CN f, were prepared. X-ray structural studies of 5a, 5b, and 5e showed that a zinc atom was positioned in a distorted tetrahedral coordination environment created by two oxazolylphenolate ligands with N,O-chelation. Hammet plots of absorption and emission maxima, respectively, in UV and photoluminescence (PL) spectra with respect to electron-donating and electron-withdrawing groups of the substituents indicate a direct correlation between the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) band gaps and electronic alterations at the ligand sites. A similar correlation was also observed for the reduction and oxidation potentials in cyclic voltammograms (CVs). A gradual increase in the HOMO-LUMO band gap is seen from electron-donating to electron-withdrawing functional groups, NMe 2 < OMe < Ph < Cl < F 2 < CN. An emission peak with a maximum at 455 nm was achieved when the most electron-withdrawing group (cyano) was applied to the oxazolylphenolate ligand system. Density-functional theory (DFT) calculations on the HOMOs and LUMOs for this series lead to a conclusion similar to that arrived at from a blue-shift trend observed in UV data and trends in the CVs. The 4-coordinated zinc complex ( 5c) was shown to be a potential blue-emitting material, exhibiting a maximum efficiency of 1720 cd/m (2) at 17 V with 0.3 cd/A in a multilayered device structure of ITO/NPB/ 5c/BCP/Alq 3/LiF/Al. On the basis of the low HOMO level of this series, 5a was tested as a hole-transporting material; this resulted in the successful fabrication of a multilayered device of ITO/ 5a/DPVBI/Alq 3/LiF/Al with an efficiency of 7000 cd/m (2) at 13 V with 2.0 cd/A.

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