Novel coumarin-based containing denrons selective fluorescent chemosesor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a novel coumarin-based dendrons derivative CD and its chemical structure was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. The sensor CD showed an obvious “on-off” fluorescence quenching response toward Cu²⁺ with a maximum quenching efficiency of 99.8%. The CD-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions. The detection limit of the sensor CD was 0.29?×?10^?6?M to Cu²⁺ and 2.39?×?10^?9?M to PPi. In addition, the sensor CD showed a 1:1 binding stoichiometry to Cu²⁺ and the sensor CD-Cu²⁺ showed a 2:1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.2). The stable pH range of sensor CD to Cu²⁺ and CD-Cu²⁺ to PPi was from 3 to 8.     

Facile Synthesis of Second-Generation Dendrons with an Orthogonal Functional Group at the Focal Point

Facile synthesis of second-generation dendrons with an aldehyde, epoxy, or t-Boc group at the focal point and nine carboxylic acid groups at the periphery is reported. The scheme includes a coupling of the first-generation dendrons and a two-step, one-pot reaction that proceeds through a Boc deprotection and in situ conjugation at the focal point.     

AB3 building blocks for the synthesis of polyester dendrimers

Syntheses of several examples of a new type of trivalent building blocks for the preparation of aliphatic polyester dendrimers are presented. Starting from the well-known mono-O-benzylidenepentaerythritol, AB₃ type acid dendrons can be obtained in high yield in only two steps. Other triprotected bis-2,2-(hydroxymethyl)-3-hydroxypropanoic acid derivatives with varying protecting groups were also synthesized readily. This type of dendron was used in combination with 2,2′-bis(hydroxymethyl) propanoic acid (bis-HMPA) divalent dendrons to produce low generation mixed polyester dendrimers with increased number of branching points.     

Decorating step-by-step and independently the surface and the core of dendrons

Dendrons possessing one activated vinyl group at the core and several chlorine atoms at the end of the branches are used as starting materials to study the possibility to react independently the surface functions and the core function. In particular, the most powerful sequence of reactions for decorating them by organometallic complexes as end groups and amine or alcohol at the core has been determined. In the first step, phenol phosphines are grafted as end groups of the dendrons, and they can be used for the complexation of metals. However, these phosphines must be kept free when amines are used to react with the vinyl core in the next step. Depending on the type of phosphine end groups and on the type of function of the core (amine or alcohol), the complexation of ruthenium ([RuCl₂(p-cymene)]₂) and rhodium ([RhCl(COD)]₂) derivatives by the phosphine end groups can occur without side reaction at the core.     

Synthesis of poly(pyridylthioether) dendrimers incorporating a Fe2(CO)6 cluster core

New pyridylthioether-based dendrons bearing a thiol moiety at their focal point have been prepared by a convergent synthetic approach. These dendrons were readily attached to a Fe₂(CO)₆ core to generate two-directional dendritic molecules incorporating an iron-carbonyl cluster.     

A conformation study of polyelectrolyte-dendritic surfactant complexes in dilute solutions

<正>Three dendronized polymers from generation one to generation three have been prepared by complexing negatively charged Frechet-type dendrons with a polyanion,poly(diallydimethylammonium chloride)(PDADMAC).The grafting degree has been confirmed mainly by elemental analysis.In dilute solutions of tetrahydrofuran,static light scattering studies indicate that the first generation complex has a coil-like conformation,even more flexible than PDADMAC.The second and third generation complexes exhibit polyelectrolyte behavior.Dynamic light scattering experiments indicate that all the three complexes have almost the same hydrodynamic radius,indicating that they might own similar coil conformation.Atomic force microscopy shows the existence of disordered globules formed by one or a couple of complex coils.All these observations can be explained by the flowerlike coil conformation,which is formed by the intra-molecular association.This is totally different from the stretched chain conformation formed by covalently connected dendronized polymers.This result also explains why some ordered supramolecular structures,found in condensed state of the similar complexes,are not as perfect as those of conventional dendronized polymers.