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In the ideal case, a precise synthesis yields molecules with a constitutional as well as a conformational perfectness. Such a case of precision is demonstrated by the synthesis of semi-rigid amphiphilic polyphenylene dendrimers (PPDs). Polar sulfonate groups are precisely placed on their periphery in such a manner that patches of polar and non-polar regions are created. Key structural features are the semi-rigid framework and shape-persistent nature of PPDs since the limited flexibility introduces a nano-phase-separated amphiphilic rim of the dendrimer. This results in both attractive and repulsive interactions with a given solvent. Frustrated solvent structures then lead to a remarkable solubility in solvents of different polarity such as toluene, methanol, and water or their mixtures. Water solubility combined with defined surface structuring and variable hydrophobicity of PPDs that resemble the delicate surface textures of proteins are important prerequisites for their biological and medical applications based upon cellular internalization. [ABSTRACT FROM AUTHOR]

Cp*TiCI[sub2](L) [L = C[sub3]H[sub3]N[sub2] (1), 3,5-Me[sub2]C[sub3]HN[sub2] (2) and 3,5-[supi]Pr[sub2]C[sub3]HN[sub2] (3)], and Cp*Ti(C[sub3]H[sub3]N[sub2])[sub3] (4) were prepared in moderate yields by treating Cp*TICI[sub3] with the pyrazoles in the presence of Et[sub3]N or with their corresponding lithium salts in Et[sub2]O. The structures of 1 and 2 determined by X-ray crystallography indicate that these complexes fold a distorted tetrahedral geometry around Ti, and the pyrazolato ligands coordinate to Ti with η[sup2]-N,N'-coordination mode. In contrast, one of the pyrazolato ligand in 4 coordinates to Ti with η[sup1]-N-bonding, whereas the other two ligands were bound to Ti with η[sup2]-N,N'-fashion. The Cp analogues, CpTiCI[sub2](L) [L = C[sub3]H[sub3]N[sub2] (5), 3,5-Me[sub2]C[sub3]HN[sub2] (6), 3,5[supi]Pr[sub2]C[sub3]HN[sub2] (7), and 3,5-Ph[sub2]C[sub3]HN[sub2] (8)], were also prepared by the reaction of CpTiCI[sub3] with the corresponding lithium saits in Et[sub2]O or n-hexane. The crystallographic analyses of 5 and 6 revealed that the pyrazolato ligands coordinate to Ti with η[sup2]-N,N'-coordination mode. These complexes (1-3, 5-8) exhibited moderate catalytic activities for ethylene polymedzation in the presence of methylaluminoxane (MAO), and the actMties were highly affected by the substituent on the pyrazolato ligand employed. Complex 1 exhibited the highest activity affording polymer with uniform molecular weight distribution, suggesting that the polymerization proceeded with uniform catalytically active species. An increase in the steric bulk in the pyrazolato ligand led to a slight decrease in the activity by the Cp* analogues, whereas the activity by the Cp analogues increased upon increasing the steric bulk in the pyrazolato ligand employed. [ABSTRACT FROM AUTHOR]

The 3‐ and 4‐aminophenylacetylenes protected by t‐butoxycarbonyl (t‐Boc) and 9‐fluorenylmethoxycarbonyl (Fmoc) groups (3a–6a) were synthesized and polymerized using [(nbd)RhCl]2 (1) and [(nbd)Rh+‐η6‐PhB−Ph3] (2) catalysts. The t‐Boc‐containing polymers [poly(3a) and poly(4a)] were obtained in high yield (82–91%). Among the Fmoc‐protected monomers, the para‐derivative polymerized well [poly(6a); yield = 85–94%], whereas its meta‐substituted analogue did not afford high molecular weight polymer in good yield [poly(5a); yield = 10–15%]. The use of KN(SiMe3)2 as a cocatalyst in conjunction with 1 led to a dramatic increase in the molecular weight of the polymers. The acid‐ and base‐catalyzed removal of the t‐Boc and the Fmoc groups, respectively, generated primary amine‐containing polymers [poly(3b)–poly(6b)] which cannot be obtained directly by the polymerization of the corresponding monomers. The solubility characteristics of the polymers bearing protected amino groups were quite different from those of the unprotected ones, the former being soluble in polar solvents, whereas the latter displayed poor solubility even in polar protic or highly polar aprotic solvents. The attempts to accomplish the free‐standing membrane fabrication by solution casting were successful only for poly(3a), and an augmentation in the gas permeability and CO2/N2 permselectivity was discerned in comparison with the unsubstituted poly(phenylacetylene) and poly(m‐t‐butyldimethylsiloxyphenylacetylene). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1853–1863, 2009 [ABSTRACT FROM AUTHOR]

Abstract: The present study deals with the application of Rh complexes possessing a phenoxy-imine ligand (1 and 2), a β-diiminate ligand (3 and 4), and ammonia ligands (5) as catalysts in the polymerization of substituted acetylenes (6a–h). All the catalysts (1–5) were effective for the polymerization of monosubstituted acetylenes (6a–e) and afforded polymers in moderate to high yields with high molecular weights (M n =15,000–93,000), and the presence of cocatalyst was not a strict requisite in the present polymerization systems in contrast to conventional [Rh(nbd)Cl]2 and [Rh(cod)Cl]2 catalysts. In the case of phenoxy-imine catalysts, the nbd-bearing one (1) was more active than the cod-bearing counterpart (2) in accordance to the general behavior of Rh catalysts, while the opposite trend was observed for β-diiminate catalysts (3 and 4). Catalyst 2 exhibited the highest activity among all the catalysts examined in the polymerization of phenylacetylene (6a) and afforded the highest molecular weight poly(6a) (M n =93,000) in almost quantitative yield. Introduction of electron-donating groups at meta and para positions of 6a (monomers 6b–d) resulted in the decrease of polymer yields. Et3N and n-C4H9Li exerted cocatalytic effects when combined with 1–5 in the polymerization of 6a, resulting in the increase of both polymer molecular weight and yield. [Copyright &y& Elsevier]

Back Cover: Like an artist, a chemist can decorate different functionalities on shape‐persistent materials. Positioning of polar and nonpolar patches on the periphery of semi‐rigid polyphenylene dendrimers leads to remarkable solubility in solvents of different polarity such as toluene, methanol, and water. Precise surface structuring and the adjustment of size, shape, and lipophilicity/polarity resembles the delicate surface textures of proteins. Further details can be found in the article by R. Stangenberg, I. Saeed, S. L. Kuan, M. Baumgarten, T. Weil, M. Klapper, and K. Müllen* on page 152. [ABSTRACT FROM AUTHOR]

Objective: To evaluate perforation of an air-bone gap closure success using fascia-cartilage composite graft in endoscopic Trans canal tympanoplasty. Study Design: Randomized Control Trial (Clinical Trials.gov Identifier: NCT04945811). Place and Duration of Study: ENT Department Combined Military Hospital, Quetta Pakistan, from Apr 2020 to May 2021. Methodology: One hundred and thirty-three cases of chronic Suppurative otitis media fulfilling the selection criteria were operated upon, and an endoscopic fascia-cartilage composite graft was used. A successful outcome in terms of perforation closure and air-bone gap closure was evaluated in all patients. Results: In the 138 patients operated, complete fascia-cartilage composite graft uptake was achieved in 129 (93.5%) patients. Nine (6.5%) patients had graft failure. The pre-operative mean air-bone gap was 36.49±4.61 decibels, and the postoperative mean air-bone gap was 12.57±5.09 decibels. This improvement was found to be significant, with the p-value < 0.001. Conclusion: Endoscopic per-meatal fascia-cartilage composite grafting has a high graft uptake and air-bone gap closure percentage in chronic Suppurative otitis media cases. [ABSTRACT FROM AUTHOR]

Objective: To compare the recovery of patients in both groups having acute otitis externa induced by cotton buds/various objects. One group by old method and second group by unique method. Study Design: Quasi-experimental study. Place and Duration of Study: Pakistan Naval Ship Shifa Karachi, from Jan to Dec 2020. Methodology: Non-probability convenience sampling technique was applied. Out of 50 cases were selected for group 1 management. Fifty cases were selected for group 2 management. A chi-square test was applied to compare the recovery of two groups of patients on the 14th day and 42nd day of follow-up. p-value was kept 0.05 as significant. Results: A total of 100 cases were treated in 2 groups. The gender distribution of the study was 54 females and 46 males. The mean age of the study population was 33.09 ± 12.93 years. p-value was calculated on the 14th day and 42nd days. A 2x2 table of 14th follow up day showed recovery by both groups with a p-value of 0.041 which is <0.05. This showed that group 2 management was statistically better than group 1 management. Conclusion: The second group was managed with eardrops containing Betamethasone and Neomycin. This management protocol is unique and better than conventional management as done in the first group. [ABSTRACT FROM AUTHOR]

Objective: To evaluate perforation of an air-bone gap closure success using fascia-cartilage composite graft in endoscopic Trans canal tympanoplasty. Study Design: Randomized Control Trial (Clinical Trials.gov Identifier: NCT04945811) Place and Duration of Study: ENT Department Combined Military Hospital, Quetta Pakistan, from Apr 2020 to May 2021 Methodology: One hundred and thirty-three cases of chronic Suppurative otitis media fulfilling the selection criteria were operated upon, and an endoscopic fascia-cartilage composite graft was used. A successful outcome in terms of perforation closure and air-bone gap closure was evaluated in all patients. Results: In the 138 patients operated, complete fascia-cartilage composite graft uptake was achieved in 129 (93.5%) patients. Nine (6.5%) patients had graft failure. The pre-operative mean air-bone gap was 36.49±4.61 decibels, and the postoperative mean air-bone gap was 12.57±5.09 decibels. This improvement was found to be significant, with the p-value < 0.001. Conclusion: Endoscopic per-meatal fascia-cartilage composite grafting has a high graft uptake and air-bone gap closure percentage in chronic Suppurative otitis media cases. [ABSTRACT FROM AUTHOR]