Cationic Carbene Analogues: Donor-Free Phosphenium and Arsenium Ions

Carbenes and their analogues have constantly enthralled chemists with their intriguing reactivity of ambiphilic character stemming from their electronic structures. Phosphenium and arsenium ions are fiercely reactive cationic species, the stabilization of which has been so far achieved in the condensed phase by dispersing the positive charge through electromeric conjugation with at least one electron-rich substituent (frequently amido groups). Although observed in the gas phase, the isolation of dicoordinate phosphenium and arsenium ions lacking such stabilizing ligands has eluded chemists for decades. Herein we show that by judicious choice of aromatic substituents, dicoordinate, donor-free, Lewis-superacidic phosphenium and arsenium ions can be kinetically stabilized. They feature singlet electronic ground states possessing a vacant p-orbital and an electron lone pair with predominantly s-character.

Bulky Polyfluorinated Terphenyldiphenylboranes: Water Tolerant Lewis Acids

Protocols for the synthesis of the bulky polyfluorinated triarylboranes 2,6‐(C₆F₅)₂C₆F₃B(C₆F₅)₂ (1), 2,6‐(C₆F₅)₂C₆F₃B[3,5‐(CF₃)₂C₆H₃] (2), 2,4,6‐(C₆F₅)₃C₆H₂B(C₆F₅)₂ (3), 2,4,6‐(C₆F₅)₃C₆H₂B[3,5‐(CF₃)₂C₆H₃] (4) were developed. All boranes are water tolerant and according to the Gutmann‐Beckett method, 1–3 display Lewis acidities larger than that of the prominent B(C₆F₅)₃.

Intramolecular Reaction of Transient Phosphenium and Arsenium Ions Giving Rise to Isolable 9-Phospha- and 9-Arsena-Fluorenium Ions

Transient phosphenium and arsenium ions, generated by fluoride abstraction from bis(m-terphenyl)fluoropnictogens, underwent intramolecular electrophilic attack prior to methyl group migration and gave rise to isolable 9-phospha- and 9-arsena-fluorenium ions.

Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays

OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu–C and Cu–P bonds represents an underexplored type of luminophore. To investigate the charge transfer and structural rearrangements in this material, we apply complementary pump-probe X-ray techniques: absorption, emission, and scattering including pump-probe measurements at the X-ray free-electron laser SwissFEL. We find that the excitation leads to charge movement from C- and P- coordinated Cu sites and from the phosphorus atoms to phenyl rings; the Cu core slightly rearranges with 0.05 Å increase of the shortest Cu–Cu distance. The use of a Cu cluster bonded to the ligands through C and P atoms is an efficient way to keep structural rigidity of luminophores. Obtained data can be used to verify computational methods for the development of luminophores.

OLED materials based on thermally activated delayed fluorescence have promising efficiency. Here, the authors investigate an organometallic multicore Cu complex as luminophore, by pump-probe X-ray techniques at three different facilities deriving a complete picture of the charge transfer in the triplet excited state.

Tri- and Tetranuclear Metal-String Complexes with Metallophilic d10 -d10 Interactions

The reaction of 2,6-F2 C6 H3 SiMe3 with Ph2 PLi provided 2,6-(Ph2 P)2 C6 H3 SiMe3 (1), which can be regarded as precursor for the novel anionic tridentate ligand [2,6-(Ph2 P)2 C6 H3 ]- (PCP)- . The reaction of 1 with [AuCl(tht)] (tht=tetrahydrothiophene) afforded 2,6-(Ph2 PAuCl)2 C6 H3 SiMe3 (2). The subsequent reaction of 2 with CsF proceeded with elimination of Me3 SiF and yielded the neutral tetranuclear complex linear-[Au4 Cl2 (PCP)2 ] (3) comprising a string-like arrangement of four Au atoms. Upon chloride abstraction from 3 with NaBArF 4 (ArF =3,5-(CF3 )2 C6 H3 ) in the presence of tht, the formation of the dicationic tetranuclear complex linear-[Au4 (PCP)2 (tht)2 ](BArF 4 )2 (4) was observed, in which the string-like structural motif is retained. Irradiation of 4 with UV light triggered a facile rearrangement in solution giving rise to the dicationic tetranuclear complex cyclo-[Au4 (PCP)2 (tht)2 ](BArF 4 ) (5), which comprises a rhomboidal motif of four Au atoms. In 3-5, the Au atoms are associated by a number of significant aurophilic interactions. The atom-economic and selective reaction of 3 with HgCl2 yielded the neutral trinuclear bimetallic complex [HgAu2 Cl3 (PCP)] (6) comprising significant metallophilic interactions between the Au and Hg atoms. Therefore, 6 may be also regarded as a metallopincer complex [ClHg(AuCAu)] between HgII and the anionic tridentate ligand [2,6-(Ph2 PAuCl)2 C6 H3 ]- (AuCAu)- containing a central carbanionic binding site and two "gold-arms" contributing pincer-type chelation trough metallophilic interactions. Compounds 1-6 were characterized experimentally by multinuclear NMR spectroscopy and X-ray crystallography and computationally using a set of real-space bond indicators (RSBIs) derived from electron density (ED) methods including Atoms In Molecules (AIM), the Electron Localizability Indicator (ELI-D) as well as the Non-Covalent Interaction (NCI) Index.

A Small Cationic Organo-Copper Cluster as Thermally Robust Highly Photo- and Electroluminescent Material

Organic light-emitting diodes (OLEDs) are revolutionizing display applications. In this aspect, luminescent complexes of precious metals such as iridium, platinum, or ruthenium still playing a significant role. Emissive compounds of earth-abundant copper with equivalent performance are desired for practical, large-scale applications such as solid-state lighting and displays. Copper(I)-based emitters are well-known to suffer from weak spin-orbit coupling and a high reorganization energy upon photoexcitation. Here we report a cationic organo-copper cluster [Cu₄(PCP)₃]⁺ (PCP = 2,6-(PPh₂)₂C₆H₃) that features suppressed nonradiative decays, giving rise to a robust narrow-band green luminophore with a photoluminescent (PL) efficiency up to 93%. PL decay kinetics corroborated by DFT calculations reveal a complex emission mechanism involving contributions of both thermally activated delayed fluorescence and phosphorescence. This robust compound was solution-processed into a thin film in prototype OLEDs with external quantum efficiency up to 11% and a narrow emission bandwidth (65 nm fwhm).

The Bis(ferrocenyl)phosphenium Ion Revisited

The bis(ferrocenyl)phosphenium ion, [Fc₂P]⁺, reported by Cowley et al. (J. Am. Chem. Soc. 1981, 103, 714–715), was the only claimed donor‐free divalent phosphenium ion. Our examination of the molecular and electronic structure reveals that [Fc₂P]⁺ possesses significant intramolecular Fe⋅⋅⋅P contacts, which are predominantly electrostatic and moderate the Lewis acidity. Nonetheless, [Fc₂P]⁺ undergoes complex formation with the Lewis bases PPh₃ and IPr to give the donor–acceptor complexes [Fc₂P(PPh₃)]⁺ and [Fc₂P(IPr)]⁺ (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazole‐2‐ylidene).

Transient Phosphenium and Arsenium Ions versus Stable Stibenium and Bismuthenium Ions

Fluoride abstraction from bis‐m‐terphenylelement fluorides (2,6‐Mes₂C₆H₃)₂EF (E=P, As) generated the highly reactive phosphenium ion [(2,6‐Mes₂C₆H₃)₂P]⁺ and the arsenium ion [(2,6‐Mes₂C₆H₃)₂As]⁺, which immediately underwent intramolecular electrophilic substitution and formation of an 1,2,4‐trimethyl‐6‐mesityl‐5‐m‐terphenyl‐benzo[b]phospholium ion and an 1,2,4‐trimethyl‐6‐mesityl‐5‐m‐terphenyl‐benzo[b]arsolium ion, respectively. The formation of the latter involved a methyl group migration from the ortho‐position of a flanking mesityl group to the meta‐position. This reactivity of [(2,6‐Mes₂C₆H₃)₂E]⁺ (E=P, As) is in sharp contrast to the related stibenium ion [(2,6‐Mes₂C₆H₃)₂Sb]⁺ and bismuthenium ion [(2,6‐Mes₂C₆H₃)₂Bi]⁺, which have been recently isolated and fully characterized (Angew. Chem. Int. Ed. 2018, 57, 10080–10084). On the basis of DFT calculations, a mechanism for the rearrangement of the phosphenium and arsenium ions into the phospholium and arsolium ions is proposed, which is not feasible for the stibenium and bismuthenium ions.

Transmetallation of bis(6-diphenylphosphinoxy-acenapth-5-yl)mercury with tin tetrachloride, antimony trichloride and bismuth trichloride

The synthesis and structure of well-defined arylelement chlorides RSnCl₄, RSnCl₃·THF, RSbCl₂, RSbCl₂·THF and RBiCl₂ is reported (R = 6-diphenylphosphinoxy-acenapth-5-yl).

A Monoaryllead Trichloride That Resists Reductive Elimination

Transmetallation of Pb(OAc)₄ with R₂ Hg (1), followed by treatment with HCl in Et₂ O, provided RPbCl₃ (2), the first kinetically stabilized monoorganolead trihalide that resists reductive elimination under ambient conditions. The kinetic stabilisation relies on an intramolecularly coordinating O-donor substituent (R=6-Ph₂ P(O)-Ace-5-). The gram-scale preparation of 2 was key for the synthesis of unsymmetrically substituted diaryllead dichlorides RR'PbCl₂ (3 a, R'=Ph; 3 b, R'=4-MeOC₆ H₄ ; 3 c, R'=4-Me₂ NC₆ H₄ ).

The Weakly Coordinating Tris(trichlorosilyl)silyl Anion

Closely following the procedure for the preparation of the base-stabilized dichlorosilylene complex NHC^Dipp ⋅SiCl₂ reported by Roesky, Stalke, and co-workers (Angew. Chem. Int. Ed. 2009, 48, 5683-5686), a few crystals of the salt [NHC^Dipp -H⋅⋅⋅Cl⋅⋅⋅H-NHC^Dipp ]Si(SiCl₃ )₃ were isolated, aside from the reported byproduct [NHC^Dipp -H⁺ ⋅⋅⋅Cl^- ], and characterized by X-ray crystallography (NHC^Dipp =N,N-di(2,6-diisopropylphenyl)imidazo-2-ylidene). They contain the weakly coordinating anion Si(SiCl₃ )₃^- , which was also obtained in high yields upon deprotonation of the conjugate Brønsted acid HSi(SiCl₃ )₃ with NHC^Dipp or PMP (PMP=1,2,2,6,6-pentamethylpiperidine). The acidity of HSi(SiCl₃ )₃ was estimated by DFT calculations to be substantially higher than those of other H-silanes. Further DFT studies on the electronic structure of Si(SiCl₃ )₃^- , including the electrostatic potential and the electron localizability, confirmed its low basicity and nucleophilicity compared with other silyl anions.

Polymorphisms in autophagy genes and active pulmonary tuberculosis susceptibility in Romania

Autophagy, a homeostatic process involved in nutrient regeneration and immune responses, may be involved in intracellular killing of M. tuberculosis. Several studies linked variation in autophagy genes with susceptibility to pulmonary tuberculosis, but others did not confirm these findings.

We genotyped single nucleotide polymorphisms (SNPs) in the ATG5 (rs2245214, c.574-12777G>C) and NOD2 (rs2066844, c.2104C>T) genes for 256 pulmonary tuberculosis patients and 330 unrelated healthy controls in Romania. Both SNPs have been reported as relevant for the autophagy process and potentially for susceptibility to active pulmonary tuberculosis.

In our study, the polymorphisms in ATG5 and NOD2 were not associated with tuberculosis. This suggests that the two genetic variants we focused on are not related to the risk for developing active TB in a Romanian population.

Analysis and structural characterization of pigments and materials used in Nicolae Grigorescu heritage paintings

The combination of various mobile, non-invasive techniques (IR reflectography technique, optical microscopy, XRF, Raman and NIR spectroscopies) and lab-based devices (FTIR and XPS spectroscopies, SEM-EDX microscopy) lead to the first exhaustive investigation of pigments and materials used by the famous Romanian painter Nicolae Grigorescu in three cultural heritage paintings. The study of a large number of spots and samples allowed a rigorous analysis and a far-reaching insight into his work.

The CARD9 Polymorphisms rs4077515, rs10870077 and rs10781499 Are Uncoupled from Susceptibility to and Severity of Pulmonary Tuberculosis

Genetic variants in the CARD9 gene predispose to inflammatory disorders and chronic infectious diseases. Tuberculosis (TB), a chronic infectious disease affecting the lung, is lethal in Card9-deficient mice. We hypothesized that polymorphisms in the CARD9 gene influence TB progression and disease-associated lung damage in humans. We tested genotype distributions of the CARD9 polymorphisms rs4077515, rs10781499 and rs10870077 in TB patients and healthy subjects in a Caucasian cohort. SNPs were in linkage disequilibrium and none of the haplotypes was significantly enriched in the TB group. We determined total and differential leukocyte count, erythrocyte sedimentation rate and plasma abundance of cytokines and chemokines as markers for systemic inflammation and scored chest X-rays to assess lung involvement in TB subjects. Most disease parameters segregated independently of the CARD9 haplotypes. In contrast to multifactorial chronic inflammation, selected genetic variants in the CARD9 gene leave host responses apparently unaffected in TB, at least in the population analyzed here.

Mixed triorganobismuthines RAr2Bi [Ar = C6F5, 2,4,6-(C6F5)3C6H2] and hypervalent racemic Bi-chiral diorganobismuth(iii) bromides RArBiBr (Ar = C6F5, Mes, Ph) with the ligand R = 2-(Me2NCH2)C6H4. Influences of the organic substituent

RAr₂Bi and chiral RArBiBr were structurally characterized; N–Bi bond distances in RArBiBr appear to be similar regardless of the electronic properties of the Ar ligand.

Morphological aspects in tuberculosis of oral cavity - our experience and a review of the literature attempt

AIM

The authors continue a started series of articles about extrapulmonary tuberculosis (EPTB) with the assessment of the mycobacterial lesions discovered on tissue samples of the oral cavity structures in the Department of Pathology of the Emergency County Hospital of Craiova, Romania, and the review of the cases reported in the literature available, between 1990 and 2013.

MATERIALS AND METHODS

The studied material consisted, for our series, of samples obtained by biopsy or surgical excision, including the salivary glands and excluding the lymph nodes from 17 patients histopathologically diagnosed with tuberculosis and, for review series, 190 papers selected from PubMed database.

RESULTS

The number of cases reported increased throughout the studied period. Most cases came from departments connected with oral pathology but also from various medical and surgical departments. In general, patients were adults with a mean age of around 40 years, with twice as many men than women, without no information or no clinical suspicion of tuberculosis (TB) at the admission. When reported, the provisional diagnostic was oriented most often towards neoplastic proliferation. There was no information about human immunodeficiency virus (HIV) testing in more than half of the case reports but when existed the result was two-fold more frequently negative than positive. TB lesions of the oral cavity were more often primary infections than secondary. From morphological point of view, the granuloma cellular population included both epithelioid and Langhans cells in most of the cases, the necrosis, present in most of the cases, displayed the whole range of morphological features, but mainly the acidophilic, microgranular one and the perilesional fibrosis was absent in almost all of the cases. As a whole, well-differentiated granulomas were the most frequent, usually of grade II - reactive type ("homeostatic") but with a significant contingent of grade I - hyperplastic ("protective") granulomas. Local extension was usually not present and, when present, regional lymph nodes were mainly involved. Coexistence of TB lesions with a neoplastic proliferation was very rare and when present it was mainly located in the parotid gland. Apart from this general profile, particular, individual profiles were observed for each of the oral cavity segments.

CONCLUSIONS

TB lesions in the oral cavity are indeed a rare event but no swelling or ulcer in the oral cavity should be disregarded by the medical practitioners because it could be tuberculosis.

Synthesis and structural characterization of substituted phenols with a m-terphenyl backbone 2,4,6-R3C6H2OH (R=2,4,6-Me3C6H2, Me5C6)

Substituted phenols with a m-terphenyl backbone 2,4,6-R3C6H2OH [R=2,4,6-Me3C6H2 (1), Me5C6 (2)] were synthesized using Kumada cross-coupling reactions between 2,4,6-I3C6H2OH and the corresponding Grignard reagent. Both compounds were structurally characterized in solution by 1H and 13C NMR spectroscopy and HRMS. The molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction.

Lymph node tuberculosis - an attempt of clinico-morphological study and review of the literature

AIM

The authors assessed the mycobacterial lesions in the lymph nodes discovered on tissue samples coming from the surgical stage in the Department of Pathology, Emergency County Hospital of Craiova, Romania, starting from 1990 until 2012.

MATERIALS AND METHODS

The studied material consisted of lymph node (LN) tissue samples obtained by biopsy or surgical excision from 362 patients histopathologically diagnosed with tuberculosis. For confirming the diagnosis, Ziehl-Neelsen staining was carried out and, in some cases, PCR technique was used.

RESULTS

Patients were mainly women, with a mean age of 35 years. The suspicion of diagnosis at admission was reduced, the most usual diagnosis being a very general and uncertain one of "adenopathy/polyadenopathy". In only few cases, other tissues/organs have been affected in the same time with the LN determination. Also, multiple LN group involvement was present in only five cases. The most affected LN groups were: the lateral cervical, submandibular, axillary, inguinal, supraclavicular and mesenteric. In paired LN groups, there was no predilection for any of the body sides. Epithelioid cells (ECs) and giant Langhans cells (GLCs) were present together in most of the granulomatous reactions. However, the presence of neutrophils in 10% of the cases should be noticed. Necrosis was present in almost all cases, displaying the whole range of morphological features, but usually the acidophilic, microgranular one. Fibrosis was rarely encountered. As a whole, well-differentiated granulomas were the most frequent but the presence of hyporeactive granulomas in more than a quarter of the cases and that of non-reactive granulomas in more than 10% of the cases should be noticed. The extension of TB process was not a rare event.

CONCLUSIONS

LNs seem to be the favorite location of TB besides the lung. The overall morphological picture revealed an active and destructive profile of the bacillary aggression in the LN parenchyma, which could mean either a higher sensitivity of the LN tissue or a more vulnerable background of the patients with TBLN lesions.

A profile of lung carcinomas: study on 364 cases

The authors have proposed to analyze retrospectively the clinical-morphological profile of a consistent group of lung carcinomas treated surgically. The studied material consisted of clinical and pathological medical records from 364 patients confirmed histopathologically with lung carcinoma after surgical intervention. Five main groups were defined based on the histopathological criteria and then compared. The assessment of clinical data, in spite of a wide range of clinical expressions, revealed some particular features for each of the defined groups. The morphological data outlined also different behavioral profiles for each of the histopathological types of lung carcinoma. These results showed that malignant epithelial tumors of the lung are still a major challenge from the detection until the therapeutic intervention and, therefore, the preoperative clinical-morphological investigation is crucial for a better adjustment of the therapeutic act according to the individual profile of each type of tumor.

A combined imagistic and morphological approach of lung tumors: study on 64 cases

Lung cancer is currently one of the major health problems, being considered one of the most common causes of death by cancer worldwide. That is why establishing as early as possible a diagnosis in order to start an appropriate therapy still a challenge. The studied group consisted of 64 patients who were investigated following the next algorithm: chest X-ray, bronchoscopy, guided bronchial brushing and/or bronchoalveolar lavage followed by cytological examination and if possible, endobronchial biopsy followed by histopathological examination. Patients were usually men, aged over 60 years coming from an urban area, smokers and with symptoms evoking the presence of neoplasia. Tumors presented as large tumoral masses, placed centrally and with obvious local spread, protruding or pushing intraluminally with subsequent bronchial stenosis, usually complicated with ulceration and bleeding, which proved to be, when histopathological examination was possible, firstly squamous carcinomas and then small cell carcinomas. The imagistic investigation in conjunction with the cytological evaluation can establish the diagnosis of malignancy of centrally located lung tumors in almost 80% of cases. The diagnosis can be improved by increasing the number of biopsy sampling and/or by the immunohistochemical marking of the cytological samples.

(2,4,6-Trimethyl-phen-yl)boronic acid-triphenyl-phosphine oxide (1/1)

In the crystal structure of the title compound, C(9)H(13)BO(2)·C(18)H(15)OP, there are O-H⋯O hydrogen bonds between the O atom of triphenyl-phosphine oxide and one hy-droxy group of the boronic acid. Boronic acid mol-ecules form inversion-related hydrogen-bonded dimers in an R(2) (2)(8) motif. The structure is consolidated by inter-molecular C-H⋯O bonds and C-H⋯π inter-actions.

2′-Iodo-2,2′′,3,3′′,4,4′′,5,5′′,6,6′′-decamethyl-1,1′:3′,1′′-terphenyl chloroform monosolvate

The title compound, C₂₈H₃₃I·CHCl₃, forms dimers through C—I⋯π inter­actions. The crystal structure is consolidated by the presence of C—H⋯π inter­actions between the chloro­form solvent and the main mol­ecule.

Pleurisies - the experience of "Tudor Vladimirescu" Hospital of Pneumology II: morphological study

Pleural effusions are still representing a challenge in daily practice.

MATERIALS AND METHODS

This retrospective study on 221 patients with pleurisies hospitalized in our unit is focused on the contribution of different types of pleural fluid morphological evaluation in setting a correct etiological diagnosis. The algorithm of investigation included: gross aspects assessment on X-ray records and by direct observation of pleural liquid obtained by thoracentesis and microscopic assessment on cytology slides of pleural fluid and on histopathological samples obtained by pleural needle biopsies.

RESULTS

Mycobacterial etiology was the most frequent, with 72% of all cases, followed by tumoral etiology. Cytologic examination of pleural fluid was useful in establishing the final diagnosis in 66.1% of cases, histopathological assessment being imposed for the rest of cases.

DISCUSSION

Imagistic investigation offered appropriate information concerning the site and extention of pleural effusions and guided, in certain cases, the needle biopsy. Gross aspect of pleural fluid oriented quite well the suspicion diagnosis. The use of a set of cytological "formulas" was useful in filtering subsequently the suspicion diagnosis. Histopatholgical examination of pleural tissue samples established the final diagnosis in cases where etiology was still uncertain after laboratory and cytological examination and subtyped further the pathologic processes within each main category of etiology.

CONCLUSIONS

A correct diagnosis of pleural effusions could be achieved only by going through a precise algorithm of investigation where, besides thorough clinical examination and laboratory tests especially of pleural liquid, morphological assessment and in particular cytologic examination of pleural liquid and histopatological examination of pleural tissue samples are essential.

3,5-Dibromo-2',3',4',5',6'-penta-methyl-1,1'-biphen-yl

In the crystal structure of the title compound, C(17)H(18)Br(2), the benzene rings are almost perpendicular [dihedral angle = 84.0 (3)°]. The crystal structure is consolidated by the presence of C-Br⋯π inter-actions.

Chloridobis{2-[(dimethyl-amino)-meth-yl]phen-yl}anti-mony(III)

In the title compound, [Sb(C(9)H(12)N)(2)Cl], the Sb atom adopts a Ψ-trigonal-bipyramidal geometry. The two 2-[(dimethyl-amino)-methyl]-phenyl ligands are coordinated asymmetrically to the Sb atom. The carbon atoms of one of the ligands are disordered over sets of sites with equal occupancy, resulting in two conformational isomers in the crystal. The Sb-C and Sb-N distances in the ordered ligand are: 2.153 (4) and 3.326 (5) Å, respectively. The corresponding distances in the disordered ligand are: 2.103 (5)/2.188 (5) and 2.454 (3) Å, respectively. The structure displays intra-molecular C-H⋯Cl hydrogen bonding.

[Pleural effusions--experience of Pneumo-phtisiology Hospital Tudor Vladimirescu--I: Clinical study]

Pleural effusions still represent major problem of respiratory tract pathology because of the invalidity potential of pleural involvement and because of the increasing incidence of diseases frequently accompanied by pleural effusion such as tuberculosis and malignant pleural proliferations. The retrospective study concerned 221 cases with pleural effusions divided into three groups depending on the etiology (bacillary, neoplastic and others). Two categories of features were assessed: parameters assessed in the first 48 hours (epidemiological data, history data, clinical data, IDR and sedimentation rate) and parameters assessed after thoracentesis and/or pleural biopsy (LDH in pleural fluid and BK presence in pleural fluid and biopsy specimens). Bacillary etiology was dominating the studied group but possibly because the hospital was well known as a mainly antituberculous medical unit. The main profile of the investigated patients was: man, teenaged or adult, smoker and often alcoholic living in town. Clinical appearance was influenced by the triad: etiologic agent, age, amount of pleural fluid. Reduced amount of pleural fluid was related to acute onset, usually in young men and symptomatology dominated by thoracic pain. In contrast, massive pleural effusion was related with chronic onset, dyspnea and adult or old age. LDH and glyco-pleuria values are not pathognomic but useful for diagnostic orientation but if microscopic or culture evidence of BK in pleural fluid or tissue specimens are added, the diagnostic accuracy is increasing. In conclusion, a thorough clinical examination completed with a complex panel of laboratory investigations, including biochemical microbiological and special tests from pleural fluid and also a cytological examination could guide the diagnostic in establishing the type and the cause of pleural effusion.