In nuclear waste treatment processes there is a need for improved ligands for the separation of actinides (An(III)) and lanthanides (Ln(III)). Several research groups are involved in the design and synthesis of new An(III) ligands and in the confinement of these and existing An(III) ligands onto molecular platforms giving multicoordinate ligands. The preorganization of ligands considerably improves the An(III) extraction properties, which are largely dependent on the solubility and rigidity of the platform. This tutorial review summarizes the most important An(III) ligands with emphasis on the preorganization strategy using (macrocyclic) platforms.

Multicoordinate ligands for actinide/lanthanide separations.

https://scholarblogs.emory.edu/liotta/files/2014/08/180.pdf

Synthesis and biological evaluation of novel curcumin analogs as anti-cancer and anti-angiogenesis agents

Ion and Molecular Recognition by Lower Rim 1,3-Di-conjugates of Calix[4]arene as Receptors

p-tert-Butylcalix[4]arene has been chemically modified in a regioselective manner at the 1,3-(distal) phenolic groups of the lower rim using electrophiles such as ethyl bromoacetate, chloroacetone, bromopinacolone, chloroacetonitrile, and prop-2-ynyl bromide. X-Ray diffraction analysis of one of these 1,3-derivatives reveals that it exists in a highly distorted cone conformation. Crystals of the dinitrile 7 are triclinic, space group P, with two molecules in a cell of dimensions a= 13.191 (3), b= 16.755(3), c= 10.424(1)A; α= 100.32(1), β= 93.23(1), γ= 84.89(2)°. The structure was solved by direct methods and refined by full-matrix least squares calculations; R= 0.066 for 4155 observed reflections. The two phenolic rings (A and C) are tilted (interplanar angle 102.3°) so as to place the hydroxy groups inside the cavity, whereas rings B and D bearing OCH2CN moieties are almost parallel to each other (interplanar angle 13.3°). This arrangement allows for relatively facile intramolecular hydrogen bond formation between proximal hydroxy and ether functional groups [O(H)⋯ O 2.941(3) and 2.903(3)A]. These products are useful precursors of other 1,3-disubstituted derivatives including double calixarenes and of a variety of tetrasubstituted calix[4]arenes with dual functionality on the lower rim.

Chemically modified calix[4]arenes. Regioselective synthesis of 1,3-(distal) derivatives and related compounds. X-Ray crystal structure of a diphenol-dinitrile

Durch Kondensation von p-tert-Butylphenol mit Formaldehyd sind in einem Schritt in guten Ausbeuten cyclische Oligomere erhaltlich, in denen je nach Reaktionsbedingungen vier, sechs oder acht Phenolbausteine uber Methylenbrucken verknupft sind. Die kelchartige Gestalt der stabilsten Konformation des Tetramers erklart den Namen Calixaren (calix = Kelch). In ahnlicher Weise liefert Resorcin bei der Kondensation mit einer Vielzahl von Aldehyden cyclische Tetramere mit dem gleichen Grundgerust (Resorcarene). In beiden Fallen erfordert die Herstellung keine Verdunnungsbedingungen, so das auch grosere Mengen leicht zuganglich sind. Uberdies konnen die Stammverbindungen vielfaltig modifiziert werden, wobei die phenolischen Hydroxygruppen und die Phenylringe zwei Ansatzpunkte bieten, die getrennt oder in Kombination genutzt werden konnen. Calixarene sind deshalb ideale Edukte fur die Synthese der unterschiedlichsten Wirtverbindungen und Bausteine fur die Konstruktion groserer molekularer Systeme mit definierter Struktur und Funktion. Die potentiellen Anwendungen reichen vom Einsatz als hochspezifische Liganden fur die Analytik, die Sensortechnik und die medizinische Diagnostik uber die Verwendung zur Decontaminierung von Abwassern bis hin zur Konstruktion kunstlicher Enzyme und zur Herstellung neuer Materialien fur die nichtlineare Optik oder fur ultradunne Schichten und Siebmembranen mit molekularen Poren.

Calixarene – Makrocyclen mit (fast) unbegrenzten Möglichkeiten

Various calix[4]arene tetraalkyl ethers and a calix[5]arene pentaalkyl ether substituted at the upper rim by the CMPO-like functional group –NH–C(O)–CH2–P(O)Ph2 as well as some linear model compounds have been synthesized for the first time. Their ability to extract europium, thorium, neptunium, plutonium and americium from 1 mol dm–3 aqueous HNO3 into methylene chloride or o-nitrophenyl hexyl ether was studied under various conditions. All the new oligomeric ligands, but especially the calixarene derivatives, are tremendously strong extractants compared with the commonly used CMPO [(N,N-diisobutylcarbamoylmethyl)octylphenylphosphine oxide]. Also in transport studies through supported liquid membranes their efficiency is higher than that of CMPO which shows lower transport rates even at a 10-fold concentration.

Calixarenes with diphenylphosphoryl acetamide functions at the upper rim. A new class of highly efficient extractants for lanthanides and actinides

Regioselective synthesis of calixcrowns derived from p-tert-butylcalix[5]arene

https://ris.utwente.nl/ws/files/6879881/Bohmer90double.pdf

Double and triple calix[4]arenis connected via the oxygen functions

Calix[41 arenes, in which two opposite p-positions are linked by an aliphatic chain, and their derivatives show transport or complexation properties strongly dependent on the length of this chain. Bicyclo-calix[4]arenes, a special case of 1,3-bridged calix[41 arenes, and annelated calix[41 arenes, a special case of 1 ,&bridged calix [4] arenes, are also described. Although the preferred conformation of calix[4]arenes is the coneconformation due to its stabilization by a cyclic array of hydrogen bonds between the phenolic hydroxyl goups, these molecules are flexible, with a cone to cone inversion rate of about 150 8-1 for a calix[glarene at 47OC (ref. 1). The cone (or any other) conformation may be fixed by derivatisation of the phenolic oxygens. Another possibility is, to connect two p-positions of opposite (1) or adjacent (3) phenolic units by a suitable bridge. Although partial cone or alternate conformations still are possible in these compounds, the complete ring inversion is entirely prevented by the bridge. Compounds of type 1 with (CH2 In -bridges are available by reaction of suitable diphenols with bisbromomethylated phenols in dioxane in the presence of Tic14 (ref. 2).

/pdf/calix-4-arenes-bridged-at-the-lower-rim-471tufzz0c.pdf

Calix[4]arenes bridged at the lower rim

/pdf/new-crown-ether-like-macrocycles-containing-a-nitrophenol-1kprvn45zt.pdf

New crown ether-like macrocycles containing a nitrophenol unit. Synthesis and metal ion effects on the reactivity of their acetates in transacylation reactions

Dagmar Kraft

Papers

Calixarenes with diphenylphosphoryl acetamide functions at the upper rim. A new class of highly efficient extractants for lanthanides and actinides

Regioselective synthesis of calixcrowns derived from p-tert-butylcalix[5]arene

Double and triple calix[4]arenis connected via the oxygen functions

Calix[4]arenes bridged at the lower rim

New crown ether-like macrocycles containing a nitrophenol unit. Synthesis and metal ion effects on the reactivity of their acetates in transacylation reactions