This article reports the synthesis and optical properties of three dinuclear, cationic copper complexes 2+ has a long lifetime of 22.8 ms. The long emission lifetimes are attributed to a rigid conformation that precludes the possible distortion of the copper in the excited state.
A series of mono, 1,4-di and 1,3,5-tri 4-substituted 3,6-di(2-pyridyl)pyridazines were analyzed to evaluate the substituent and steric effects in the crystal packing.Renewed interest in pyridazine chemistry arises from the potential that they have shown in the formation of polynuclear coordination assemblies with diverse topologies including [2 Â 2] grids, 1 metallocryptand cages 2 and helices.3 One of the best studied compounds in this class is 3,6-di(2-pyridyl)pyridazine and its derivatives.4b The N-atoms present multiple coordination sites and their attachments to a variety of metal centres including Cu(I), Ni(II) and Ag(I) facilitate spectroscopic investigation of the resulting photophysical, magnetic and electrochemical properties of any emerging complex array. 5Sterically demanding substituents on the pyridazine ring can force the neighbouring aromatic rings to twist away from the pyridazine ring plane, thus influencing the entire topological and coordination environment. 6 Consequently, selective substitution onto the pyridazine ring offers a mechanism for the manipulation and control of the three-dimensional nature of the assembly.Building on our growing interest in N-rich polyaromatic hydrocarbons, we have generated three aromatically 4-substituted 3,6-di(2-pyridyl)pyridazines 1, 2 and 3 (Scheme 1). ‡ These compounds were synthesized by the inverse electron demand Diels-Alder reaction between 3,6-di(2-pyridyl)-1,2,4,5-tetrazine and the corresponding alkynes.10 There is a correlation between the number of ethynyl units and the temperature employed for the reaction as represented in Scheme 2 (better yields were obtained for the less reactive di-and Scheme 1 The chemical structures of the molecules.
This article reports the preparation of a range of phenyl, pyridyl and pyrazinyl substituted pyridazines via the inverse electron demand [2 + 4] Diels-Alder reaction between 3,6-di(2-pyridyl)-1,2,4,5-tetrazines (bptz) and 3,6-di(2-pyrazinyl)-1,2,4,5-tetrazines (bpztz) and suitable dienophiles including acenaphthalene. The resulting polyaromatic compounds vary systematically in the number of aromatic substituents and the number and position of N-heteroatoms. For four of these compounds, the effect of the molecular changes on the solid-state structures were investigated using single crystal X-ray crystallography. The pyridazines were used as bidentate ligands in {M(II)(bipy) 2 } and tris(homoleptic) complexes (M = Fe, Ru). The optical and electrochemical properties of these complexes reflect the electron accepting character of the new ligands. The facial and meridional isomers of the tris complexes could be separated by column chromatography (on silica), thus allowing a spectral comparison of their absorption and emission properties. The solid-state structures of several of the metal complexes are discussed, including that of the facial isomer of the tris Ru(II) complex of 3,6-bis(2-pyridyl)-4,5-bis(4-pyridyl)pyridazine-a potential preformed geometric motif for the predirected construction of supramolecular assemblies.
The use of straight hole turbodrills in the North Sea, in vertical and deviated well applications, is discussed with reference to the optimisation of drilling performance and to the techniques employed for directional control. The adaptation of turbo drilling to maximize the benefits of STRATAPAX* bits is examined, with specific reference to well examples in the Northern North Sea. Improvements in drilling performance due to the development of the turbodrill/STRATAPAX* bit combination are analysed. INTRODUCTION Straight hole turbodrills have played an active role in North Sea drilling since their introduction to the area in 1968. They have been subject to an ever widening sphere of applications, helped by increased knowledge of North Seageology, good rig hydraulics, improved diamond bit design and the introduction of STRATAPAX* bits. Operations cover vertical and deviated drilling in hole diameters ranging from 5 7/8" to 12 1/4", and mud specific gravity as high as 2,0 in the smaller hole sizes. Current turbodrilling activities which are equally divided between development work and exploration/ appraisal drilling are described. TURBODRILLING IN VERTICAL HOLES Neyrfor straight hole turbodrills have been used with considerable success for vertical 12 1/4", 8 1/2" and 6" hole sections in exploration and appraisal wells drilled from semi-submersibles, which are generally accepted by the oil industry as the best adapted drilling unit for the North Sea area. The daily cost of such units is very high and the economic advantages of turbodrilling are evidenced by the regularity of its application. Experience has shown that the use of packed hole assemblies and extended gauge diamond bits maximizes turbodrilling performance, gives an excellent gauge hole and eliminates holespiralling. String rotation is used to ensure smooth transmission of weight to the bit and to minimise the danger of sticking problems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.