Design of organophosphorus materials for organic electronics and bio-applications

π-Extended molecules are key components for the development of materials science. In fact, polyaromatic structures are fundamental for the scientific and technological progress of fields such as organic electronics and bio-applications. Beneficial properties of π-extended structures are absorption in the visible region, often luminescence, high electron mobilities and stability. Common approaches to adjust the properties of polyaromatic structures to functional setups involve changes in shape and size at the molecular level. Recently, incorporating hetero-elements emerged as successful approach. In this regard, organophosphorus conjugated molecules are new materials holding great promise for potential applications. In this review, we comprehensively discuss the design/development of polyaromatic phosphorus materials and their applicability. We establish structure/property/applicability relationships to provide key guidelines for the engineering of newer, future applications. This article thus provides a source of information for the further development of this rapidly evolving field of research.     

Synthesis and Crystal Structure of Pd（ptac—C,N）（acac—O,O）

1INTRODUCTIONTherehasbeenconsiderableattentionfocusedonthestudyofpalladiumcomplexinorganicsynthesis,catalyticprocesses,chemicalreactivity,spectroscopyandstructuralanalysisandfunctionalmaterials[1].Manypalladacycleshavebeenappliedinthepreparationofliquid-crystallinecomplexes[2],andsomeofthemshowantitumoractivity.Theincreasingimportanceofsuchcyclo-organometalliccomplexleadsustoinvestigatethecyclicPdcomplexeswithenhancedchemicalandthermalstability,fromwhichdetailedspectroscopicandstructuralc…     

Polystyrene-supported recyclable palladacycle catalyst for Heck, Suzuki and Sonogashira reactions

A new type of soluble polystyrene-supported palladium complex as an excellent and recyclable palladacycle catalyst was discovered for carboncarbon bond formation in Heck, Suzuki and Sonogashira reactions. Precipitation and filtration process for recycling the catalyst was also achieved.     

New homochiralortho-palladated matrix bearing a bulky substituent at the carbon stereocenter

A new homochiral dimericortho-palladated complex bearing a bulkytert-butyl substituent at the carbon stereocenter was synthesized from optically activeN,N-dimethyl-α-tert-butylbenzylamine. Regioselective activation of only the aromatic C−H bond was shown to occur during the cyclometallation process proceeding under very mild conditions due to steric effects. Spectral characteristics of mononuclear derivatives of the new dimeric complex indicate that the five-membered palladacycle exists predominantly in one of two possible chiral conformations with the axial position of thetert-butyl substituent. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1375–1384, July, 1997.     

Pd催化的配体导向C—H键乙酰化反应的理论研究

Pd催化的配体导向C-H键官能化反应已经成为有机化学中一种重要的合成手段. 我们用B3PW91密度泛函方法研究了Pd催化的配体导向C-H键乙酰化反应中催化剂和底物配合步骤以及C-H键活化步骤中的热力学性质. 研究发现, 具有不同导向基团的反应物之间竞争反应的选择性取决于导向基团与Pd(OAc)₂的配合步骤, 配合反应稳定常数大的较容易生成乙酰化的产物. 另一方面, 反应的选择性与C-H键的活化步骤无关, 并且与导向基团的配位原子的气相碱性、原子上的电荷密度以及最高占据轨道能量都没有相关性.     

Ferrocenylimidazoline palladacycles as efficient catalysts for the aza‐Claisen rearrangement reaction of allylic imidates

Chloride‐bridged palladacycle dimers 1 have been evaluated as catalysts for the aza‐Claisen rearrangement of allylic imidates 2 to the corresponding allyl amides 3 . Cyclopalladated complexes 1b–e bearing electron‐donating substituents on imidazoline ring were identified as being superior catalysts because excellent yields were obtained without using silver salts for activation. In addition, a correlation between substituents on the imidazoline ring and catalytic activity of palladacycles was established. The electron‐deficient ligands and good solubility of catalysts in the reaction solution increase the catalytic activity. Copyright © 2008 John Wiley & Sons, Ltd.     

A nontransmetalation reaction pathway for anionic four-electron donor-based palladacycle-catalyzed addition reactions of arylborons with aldehydes

A nontransmetalation reaction pathway for anionic four-electron donor-based (Type I) palladacycle-catalyzed addition reactions of arylborons with aldehydes is described. This new reaction pathway offers new catalysis opportunities for Type I palladacycle-catalyzed addition reactions such as the exceptionally low catalyst loading catalysis, with the catalyst loading as low as 0.0005 mol %. This new pathway may be applicable for other transition metal-catalyzed addition reactions and might lead to the development of new reactions including sequential/tandem reactions.     

Synthesis, structure, and reactivity of palladacycles that contain a chiral rhenium fragment in the backbone: New cyclometalation and catalyst design strategies

The bromocyclopentadienyl complex [(eta5-C5H4Br)Re(CO)3] is converted to racemic [(eta5-C5H4Br)Re(NO)(PPh3)(CH2PPh2)] (1 b) similarly to a published sequence for cyclopentadienyl analogues. Treatment of enantiopure (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH3)] with nBuLi and I2 gives (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH3)] ((S)-6 c; 84 %), which is converted (Ph3C+ PF6 -, PPh2H, tBuOK) to (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH2PPh2)] ((S)-1 c). Reactions of 1 b and (S)-1 c with Pd[P(tBu)3]2 yield [{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-X)}2] (10; X = b, Br, rac/meso, 88 %; c, I, S,S, 22 %). Addition of PPh3 to 10 b gives [(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(PPh3)(Br)] (11 b; 92 %). Reaction of (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH2PPh2)] ((S)-2) and Pd(OAc)(2) (1.5 equiv; toluene, RT) affords the novel Pd3(OAc)4-based palladacycle (S,S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-OAc)2Pd(mu-OAc)2Pd(mu-PPh2CH2)(Ph3P)(ON)Re(eta5-C5H4)] ((S,S)-13; 71-90 %). Addition of LiCl and LiBr yields (S,S)-10 a,b (73 %), and Na(acac-F6) gives (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(acac-F6)] ((S)-16, 72 %). Reaction of (S,S)-10 b and pyridine affords (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(NC5H5)(Br)] ((S)-17 b, 72 %); other Lewis bases yield similar adducts. Reaction of (S)-2 and Pd(OAc)2 (0.5 equiv; benzene, 80 degrees C) gives the spiropalladacycle trans-(S,S)-[{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)}2Pd] (39 %). The crystal structures of (S)-6 c, 11 b, (S,S)- and (R,R)-132 C7H8, (S,S)-10 b, and (S)-17 b aid the preceding assignments. Both 10 b (racemic or S,S) and (S)-16 are excellent catalyst precursors for Suzuki and Heck couplings.     

Mono‐ and dinuclear oxime palladacycles bearing diphosphine ligands: An unusual coordination mode for dppe

Three new oxime‐based palladacycles, namely [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(dppm)]ClO₄ ( 1 ), [Pd₂{C,N‐C₆H₄{C(Me)?NOH}‐2}₂(dppe)₂(μ‐dppe)](ClO₄)₂ ( 2 ) and [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(dppmS₂)]ClO₄ ( 3 ), were synthesized by the reaction of dinuclear oxime complex [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(μ‐Cl)]₂ with different diphosphine ligands (dppm, dppe and dppmS₂). The synthesized complexes were characterized using Fourier transform infrared, ³¹P NMR, ¹H NMR and ¹³C NMR spectroscopic methods and elemental analyses, and their molecular structures were elucidated using X‐ray crystallography. The structure of 2 is worthy of note as it is the first oxime palladacycle where there are both bridging (P–) and chelating (P^P) dppe ligands, giving rise to a dinuclear complex. The palladium atom is in a five‐coordinate, square pyramidal P₃NC environment, while in 3 the palladium atom is in a distorted square planar environment, coordinated by the oxime ligand and a chelating (S^S) dppmS₂ ligand. These complexes were employed as efficient catalysts for the Suzuki–Miyaura cross‐coupling reaction of several aryl bromides with phenylboronic acid. The in vitro cytotoxicity of the compounds was also evaluated against human tumour cell lines (HT29, A549 and HeLa) using the MTT assay method. The results indicate that the dinuclear complex 2 has greater catalytic and anticancer activity in comparison with the mononuclear complexes 1 and 3 .