554457-42-0

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• 107-85-7 1-amino-3-methylbutane 
• 3460-18-2 1,4-dibromo-2-nitrobenzene 

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• 950668-35-6 C₁₁H₁₇BrN₂ 
• 950668-39-0 C₂₀H₂₃BrN₂O 
• 1391950-77-8 pyridine-2,6-dicarboxylic acid bis[(4-bromo-2-nitrophenyl)-(3-methylbutyl)amide] 

Relevant academic research and scientific papers

Neutral Heteroleptic Lanthanide Complexes for Unravelling Host-Guest Assemblies in Organic Solvents: The Law of Mass Action Revisited

The binding of lanthanide containers [Ln(β-diketonate)3dig] [dig = 1-methoxy-2-(2-methoxyethoxy)ethane] to aromatic tridentate N-donor ligands (L) in dichloromethane produces neutral nine-coordinate heteroleptic [LLn(β-diketonate)3] complexes, the equilibrium reaction quotients of which vary with the total concentrations of the reacting partners. This problematic drift prevents the determination of both reliable thermodynamic stability constants and intrinsic host-guest affinities. The classical solution theory assigns this behavior to changes in the activity coefficients of the various partners in nonideal solutions, and a phenomenological approach attempts to quantitatively attribute this effect to some partition of the solvent molecules between bulk-innocent and contact-noninnocent contributors to the chemical potential. This assumption eventually predicts an empirical linear dependence of the equilibrium reaction quotient on the concentration of the formed [LLn(β-diketonate)3] complexes, a trend experimentally supported in this contribution for various ligands L differing in lipophilicity and nuclearity and for lanthanide containers grafted with diverse β-diketonate coligands. Even if the origin of the latter linear dependence is still the subject of debate, this work demonstrates that this approach can be exploited by experimentalists for extracting reliable thermodynamic constants suitable for analyzing and comparing host-guest affinities in organic solvents.

Bottom-Up Approach for the Rational Loading of Linear Oligomers and Polymers with Lanthanides

The adducts between luminescent lanthanide tris(β-diketonate)s and diimine or triimine ligands have been explored exhaustively for their exceptional photophysical properties. Their formation, stability, and structures in solution, together with the design of extended metallopolymers exploiting these building blocks, remain, however, elusive. The systematic peripheral substitution of tridentate 2,6-bis(benzimidazol-2-yl)pyridine binding units (Lk = L1-L5), taken as building blocks for linear oligomers and polymers, allows a fine-tuning of their affinity toward neutral [Ln(hfa)3] (hfa = hexafluoroacetylacetonate) lanthanide containers in the [LkLn(hfa)3] adducts. Two trends emerge with (i) an unusual pronounced thermodynamic selectivity for midrange lanthanides (Ln = Eu) and (ii) an intriguing influence of remote peripheral substitutions of the benzimidazole rings on the affinity of the tridentate unit for [Ln(hfa)3]. These trends are amplified upon the connection of several tridentate binding units via their benzimidazole rings to give linear segmental dimers (L6) and trimers (L7), which are considered as models for programming linear Wolf-Type II metallopollymers. Modulation of the affinity between the terminal and central binding units in the linear multitridentate ligands deciphers the global decrease of metal-ligand binding strengths with an increase in the length of the receptors (monomer → dimer → trimer → polymer). Application of the site binding model shed light onto the origin of the variation of the thermodynamic affinities: a prerequisite for the programmed loading of a polymer backbone with luminescent lanthanide β-diketonates. Analysis of the crystal structures for these adducts reveals delicate correlations between the chemical bond lengths measured in the solid state (or bond valence parameters) and the metal-ligand affinities operating in solution.

Looking for the Origin of Allosteric Cooperativity in Metallopolymers

The basic concept of allosteric cooperativity used in biology, chemistry and physics states that any change in the intermolecular host-guest interactions operating in multisite receptors can be assigned to intersite interactions. Using lanthanide metals as guests and linear multi-tridentate linear oligomers of variable lengths and geometries as hosts, this work shows that the quantitative modeling of metal loadings requires the consideration of a novel phenomenon originating from solvation processes. It stepwise modulates the intrinsic affinity of each isolated site in multisite receptors, and this without resorting to allosteric cooperativity. An easy-to-handle additive model predicts a negative power law dependence of the intrinsic affinity on the length of the linear metallopolymer. Applied to lanthanidopolymers, the latter common analysis overestimates cooperativity factors by more than two orders of magnitude.

N-Heterocyclic tridentate aromatic ligands bound to [ln(hexafluoroacetylacetonate)3] units: Thermodynamic, structural, and luminescent properties

Herein, we discuss how, why, and when cascade complexation reactions produce stable, mononuclear, luminescent ternary complexes, by considering the binding of hexafluoroacetylacetonate anions (hfac-) and neutral, semi-rigid, tridentate 2,6-bis(benzimidazol-2-yl)pyridine ligands (Lk) to trivalent lanthanide atoms (LnIII). The solid-state structures of [Ln(Lk)(hfac)3] (Ln=La, Eu, Lu) showed that [Ln(hfac)3] behaved as a neutral six-coordinate lanthanide carrier with remarkable properties: 1)the strong cohesion between the trivalent cation and the didentate hfac anions prevented salt dissociation; 2)the electron-withdrawing trifluoromethyl substituents limited charge-neutralization and favored cascade complexation with Lk; 3)-nine-coordination was preserved for [Ln(Lk)(hfac) 3] for the complete lanthanide series, whilst a counterintuitive trend showed that the complexes formed with the smaller lanthanide elements were destabilized. Thermodynamic and NMR spectroscopic studies in solution confirmed that these characteristics were retained for solvated molecules, but the operation of concerted anion/ligand transfers with the larger cations induced subtle structural variations. Combined with the strong red photoluminescence of [Eu(Lk)(hfac)3], the ternary system LnIII/hfac -/Lk is a promising candidate for the planned metal-loading of preformed multi-tridentate polymers.

Respiratory syncytial virus fusion inhibitors. Part 5: Optimization of benzimidazole substitution patterns towards derivatives with improved activity

Extensive SAR studies and optimization of ADME properties of benzimidazol-2-one derivatives led to the identification of BMS-433771 (3) as an orally active RSV fusion inhibitor. In order to extend the structure-activity relationships for this compound ser