Synthesis and investigation of intra-molecular charge transfer state properties of novel donor-acceptor-donor pyridine derivatives: the effects of temperature and environment on molecular configurations and the origin of delayed fluorescence

A novel series of donor-acceptor-donor (D-A-D) structured pyridine derivatives were synthesised and detailed photo-physical investigations were made using mainly steady-state and time-resolved spectroscopy techniques at varying temperatures. The investigations showed that the molecules have solvent polarity and temperature dependent excited-state configurations, confirmed in two different polarity solvents (295-90 K), i.e. methyl cyclohexane (MCH) and 2-methyltetrahdrofurane (2-MeTHF). In MCH, the investigations revealed dual fluorescence over the temperature range of 295-90 K. At 295 K, the ground-state configuration of the molecules has a partially twisted geometry as determined by DFT calculation, yet the emission originates totally from a locally excited (LE) state, however once the temperature is lowered to 90 K, the twisted molecular configuration is stabilised, and the emission originates from a fully-relaxed intramolecular charge transfer state (ICT), this is contrary to the systems where structural reorganisation stabilises ICT and this is frozen out at low temperatures. The DFT calculations revealed different ground state molecular configurations due to the presence of different electron-donating groups, e.g. the molecule including anthracene groups has a near 901 twisted geometry whereas the triphenylamine including molecule has a pyramidal geometrical folding, therefore, the decrease in temperature restricts the donor degree of rotational freedom. In 2-MeTHF solution, the fluorescence spectrum of both molecules is always of ICT character, but gradually red-shifts through the fluid to glass transition temperature (B135 K), in this case, the fluorescence occurs after structural and solvent-shell relaxations, however, upon cooling below 135 K, the spectra dramatically shift back to blue giving rise to strong emission from an ICT excited-state (but not the LE state) where the molecules have unrelaxed geometries. This significant change in the nature of the emitting species was explained with specific solvent-solute dynamic interactions in the vicinity of the solvation shell and the effect of thermal excitation of molecular vibrational modes of the C-C bond linking donor and acceptor units. Finally, we confirmed that the molecules have ICT ground-state geometry in the solid-state phase (spin-coated films), and the time-resolved decay dynamics were investigated comparing the spin-coated films (at RT and 25 K) and MCH solutions (at 295 K and 90 K)

High efficiency OLEDs based on anthracene derivatives: The impact of electron donating and withdrawing group on the performance of OLED

New well-defined bulky anthracene derivatives with side groups having electron donating or withdrawing properties 8a-d were synthesized. The compounds contain substituted anthracene as the central core attaching 2-(4-(2-pyridinyl)- phenyl)vinyl and 4-R-phenyl [R: H (a), OMe (b) and CF3 (c), N(Ph)2 (d)] groups at 9- and 10- positions. The impact of electron donating, withdrawing and neutral groups and their influence on the molecules photophysical, charge transfer (CT), triplet transfer (TT) and triplet-triplet annihilation (TTA) properties has been investigated. Based on the photophysical studies the most promising molecule (8d) has been selected and high efficiency fluorescent OLEDs with EQE at very low current efficiency reaching 7% were obtained. The value at low current density implies a Triplet Fusion (TF) contribution of 45%, very close to the maximum theoretical value of 50% when only the singlet decay channel is open to TTA, however we believe that in this case both TTA and TADF contribute to the triplet harvesting to yield high EQE values, and this mixed triplet harvesting arises through the heterogeneity of the films. At high current density a brightness of 20000 cd/m2 was achieved and it is assigned partially to the material crystallisation. © 2015 Elsevier B.V.Devlet Planlama Örgütü Engineering and Physical Sciences Research CouncilF.T. gratefully acknowledge the (Turkish) State Planning Organization (DPT) for Financial support. G.H. also thanks Turkish DPT for financial support for her MSc. The authors are grateful to Dr. Serife Sarioglan for her initial help in electrochemistry measurements. OEM group at Physics Department/Durham University would like to thank EPSRC for partial financial support of this project. Appendix

Tuberculous and brucellosis meningitis differential diagnosis

Background: The Thwaites and Lancet scoring systems have been used in the rapid diagnosis of tuberculous meningitis (TBM). However, brucellar meningoencephalitis (BME) has similar characteristics with TBM. The ultimate aim of this study is to infer data to see if BME should be included in the differential diagnosis of TBM when these two systems suggest the presence of TBM.Method: BME and TBM patients from 35 tertiary hospitals were included in this study. Overall 294 adult patients with BME and 190 patients with TBM were enrolled. All patients involved in the study had microbiological confirmation for either TBM or BME. Finally, the Thwaites and Lancet scoring systems were assessed in both groups.Results: The Thwaites scoring system more frequently predicted BME cases (n = 292, 99.3%) compared to the TBM group (n = 182, 95.8%) (P = 0.017). According to the Lancet scoring system, the mean scores for BME and TBM were 9.43 +/- 1.71 and 11.45 +/- 3.01, respectively (P < 0.001). In addition, TBM cases were classified into "probable" category more significantly compared to BME cases, and BME cases were categorized into the "possible" category more frequently.Conclusions: When the Thwaites or Lancet scoring systems indicate TBM, brucellar etiology should also be taken into consideration particularly in endemic countries. (C) 2015 Elsevier Ltd. All rights reserved

Cranial imaging findings in neurobrucellosis: results of Istanbul-3 study.

OBJECTIVE: Neuroimaging abnormalities in central nervous system (CNS) brucellosis are not well documented. The purpose of this study was to evaluate the prevalence of imaging abnormalities in neurobrucellosis and to identify factors associated with leptomeningeal and basal enhancement, which frequently results in unfavorable outcomes. METHODS: Istanbul-3 study evaluated 263 adult patients with CNS brucellosis from 26 referral centers and reviewed their 242 magnetic resonance imaging (MRI) and 226 computerized tomography (CT) scans of the brain. RESULTS: A normal CT or MRI scan was seen in 143 of 263 patients (54.3 %). Abnormal imaging findings were grouped into the following four categories: (a) inflammatory findings: leptomeningeal involvements (44), basal meningeal enhancements (30), cranial nerve involvements (14), spinal nerve roots enhancement (8), brain abscesses (7), granulomas (6), and arachnoiditis (4). (b) White-matter involvement: white-matter involvement (32) with or without demyelinating lesions (7). (c) Vascular involvement: vascular involvement (42) mostly with chronic cerebral ischemic changes (37). (d) Hydrocephalus/cerebral edema: hydrocephalus (20) and brain edema (40). On multivariate logistic regression analysis duration of symptoms since the onset (OR 1.007; 95 % CI 1-28, p = 0.01), polyneuropathy and radiculopathy (OR 5.4; 95 % CI 1.002-1.013, p = 0.044), cerebrospinal fluid (CSF)/serum glucose rate (OR 0.001; 95 % CI 000-0.067, p = 0.001), and CSF protein (OR 2.5; 95 % CI 2.3-2.7, p = 0.0001) were associated with diffuse inflammation. CONCLUSIONS: In this study, 45 % of neurobrucellosis patients had abnormal neuroimaging findings. The duration of symptoms, polyneuropathy and radiculopathy, high CSF protein level, and low CSF/serum glucose rate were associated with inflammatory findings on imaging analyses

Cranial imaging findings in neurobrucellosis: results of Istanbul-3 study

Objective: Neuroimaging abnormalities in central nervous system (CNS) brucellosis are not well documented. The purpose of this study was to evaluate the prevalence of imaging abnormalities in neurobrucellosis and to identify factors associated with leptomeningeal and basal enhancement, which frequently results in unfavorable outcomes. Methods: Istanbul-3 study evaluated 263 adult patients with CNS brucellosis from 26 referral centers and reviewed their 242 magnetic resonance imaging (MRI) and 226 computerized tomography (CT) scans of the brain. Results: A normal CT or MRI scan was seen in 143 of 263 patients (54.3 %). Abnormal imaging findings were grouped into the following four categories: (a) inflammatory findings: leptomeningeal involvements (44), basal meningeal enhancements (30), cranial nerve involvements (14), spinal nerve roots enhancement (8), brain abscesses (7), granulomas (6), and arachnoiditis (4). (b) White-matter involvement: white-matter involvement (32) with or without demyelinating lesions (7). (c) Vascular involvement: vascular involvement (42) mostly with chronic cerebral ischemic changes (37). (d) Hydrocephalus/cerebral edema: hydrocephalus (20) and brain edema (40). On multivariate logistic regression analysis duration of symptoms since the onset (OR 1.007; 95 % CI 1–28, p = 0.01), polyneuropathy and radiculopathy (OR 5.4; 95 % CI 1.002–1.013, p = 0.044), cerebrospinal fluid (CSF)/serum glucose rate (OR 0.001; 95 % CI 000–0.067, p = 0.001), and CSF protein (OR 2.5; 95 % CI 2.3–2.7, p = 0.0001) were associated with diffuse inflammation. Conclusions: In this study, 45 % of neurobrucellosis patients had abnormal neuroimaging findings. The duration of symptoms, polyneuropathy and radiculopathy, high CSF protein level, and low CSF/serum glucose rate were associated with inflammatory findings on imaging analyses. © 2016, Springer-Verlag Berlin Heidelberg

Liver involvement in patients with brucellosis: results of the Marmara study

WOS: 000336986700024PubMed ID: 24557334Brucellosis is a zoonotic disease that primarily affects the reticuloendothelial system. But, the extent of liver damage in due course of the disease is unclear. This study included 325 brucellosis patients with significant hepatobiliary involvement identified with microbiological analyses from 30 centers between 2000 and 2013. The patients with a parts per thousand yen5 times of the upper limit of normal for aminotransferases, total bilirubin level a parts per thousand yen2 mg/dl or local liver lesions were enrolled. Clinical hepatitis was detected in 284 patients (87.3 %) and cholestasis was detected in 215 (66.1 %) patients. Fatigue (91 %), fever (86 %), sweating (83 %), arthralgia (79 %), and lack of appetite (79 %) were the major symptoms. Laboratory tests showed anemia in 169 (52 %), thrombocytopenia in 117 (36 %), leukopenia in 81 (25 %), pancytopenia in 42 (13 %), and leukocytosis in 20 (6 %) patients. The most commonly used antibiotic combinations were doxycycline plus an aminoglycoside (n = 73), doxycycline plus rifampicin (n = 71), doxycycline plus rifampicin and an aminoglycoside (n = 27). The duration of ALT normalization differed significantly in three treatment groups (p 0.05). During the follow-up, treatment failure occurred in four patients (1 %) and relapse was seen in three patients (0.9 %). Mortality was not observed. Hepatobiliary involvement in brucellosis has a benign course with suitable antibiotics and the use of doxycycline and an aminoglycoside regimen seems a better strategy in select patients