Alicia M. Beatty

A VERSATILE ROUTE TO POROUS SOLIDS: ORGANIC-INORGANIC HYBRID MATERIALS ASSEMBLED THROUGH HYDROGEN BONDS

Square-planar and octahedral complexes of NiII and PtII link through head-to-head hydrogen bonds to form porous frameworks with large cavities that are suitable for inclusion of guest molecules. A series of four different complexes with pyridine-based ligands (in the center of the picture) are described, which contain either counterions or small molecules in channels. A=hydrogen-bond acceptor, D=hydrogen-bond donor, M=metal ion.

Organic Assemblies of 2-pyridones with Dicarboxylic Acids

Abstract The syntheses and crystal structures of four cocrystals; 2-pyridone fumaric acid (2/1), 2-pyridone meso -2,3-dibromosuccinic acid (2/1), 5-chloro-2-pyridone adipic acid (2/1) and 6-methyl-2-pyridone ( S )-malic acid (2/1), are reported. The competition between two self- and mutually-complementary hydrogen-bond moieties (carboxylic acid and 2-pyridone) are examined and compared with results obtained from an earlier study of 2-pyridone and unsubstituted aliphatic dicarboxylic acids.

Low-dimensional architectures of silver coordination compounds assembled via amide-amide hydrogen bonds

The syntheses and crystal structures of di(6-methylnicotinamide)silver(I) triflate (1), di(6-methylnicotinamide)silver(I) nitrate (2), and di(isonicotinamide)silver(I) triflate dihydrate (3) are described. Despite the structural differences in their counter-anions, both 1 and 2 exhibit very similar hydrogen-bonded networks, where a ladder motif is formed through amide-amide hydrogen bonding interactions. The para position of the amide moiety in 3 promotes chain formation through amide-amide hydrogen bonds. These structures illustrate the robust hydrogen-bonding ability of the amide functionality, even in a potentially disruptive environment of metal ions, anions and water molecules. The influence of substituents on the nicotinamide ligand and the effect of varying anions in this system are discussed.

Enantioselective synthesis of benzocyclic α,α-dialkyl-amino acids: new insight into the solvent dependent stereoselectivity of the TMSCN addition to phenylglycinol derived imines

Abstract Different benzocycloalkane-1-amino-1-carboxylic acids 1a–e have been synthesized via an asymmetric Strecker reaction using (S)-α-methylbenzylamine and (R)-phenylglycinol as chiral auxiliaries. The Zn2+-catalyzed addition of HCN to (S)-α-methylbenzylamine derived ketimines of 1-tetralone (8a) and 1-benzosuberone (8b) yielded mixtures of diastereomeric aminonitriles (1S,1′S)-10a/(1R,1′S)-10a (10:1 ratio) and (1R,1′S)-10b/(1S,1′S)-10b (56:44 ratio), respectively. These aminonitriles are converted to amino acids 1a,b in two steps. The addition of TMSCN to the (R)-phenylglycinol derived ketimines of 8a, 8b, 1-indanone (8c), 7-fluoro-1-tetralone (8d), 7-fluoro-1-benzosuberone (8e) yielded mixtures of diastereomeric trimethylsilylated aminonitriles (1S,1′R)-14a–e/(1R,1′R)-14a–e. The addition proceeded with diastereofacial selectivities ranging from 1:2.9 to 1:25. The selectivity was found to be temperature and solvent dependent. The diastereomeric ratio (dr) of aminonitriles (1S,1′R)-14a/(1R,1′R)-14a increased in different solvents in the order methanol

Organoimido-polyoxometalates as polymer pendants

The p-styrenyl substituent borne by the organoimido ligand in the Lindqvist derivative [NBu4]2[Mo6O18(NC6- H4CHCH2)] 1 allows the polyoxometalate complex to be introduced as a pendant group in polystyrene compositions via conventional free radical-induced copolymerization.

Asymmetric synthesis of two new conformationally constrained lysine derivatives

Abstract The asymmetric synthesis of the conformationally constrained l - and d -lysine derivatives methyl (1S,8S)-1-amino-8-tert-butoxycarbonylamino-1,2,3,4,5,6,7,8-octahydroanthracene-1-carboxylate ( 4 ) and methyl (1R,8S)-1-amino-8-tert-butoxycarbonylamino-1,2,3,4,5,6,7,8-octahydroanthracene-1-carboxylate ( 5 ), respectively are described. Application of the Bucherer hydantoin synthesis to the carbonyl group of 2′,3′,4′,5′,6′,7′-hexahydrospiro[1,3-ethylenedithiole-2,1′-anthracen]-8′-one ( 18 ), which was prepared from 1,8-dichloroanthraquinone ( 14 ) in nine steps and the deprotection of the masked second ketone of 18 yields rac-21. The latter is the precursor for a novel asymmetric reductive amination protocol using (R)-phenylglycinol as a chiral amino auxiliary and NaBH(OAc)3 as a reducing agent. Using this procedure, the asymmetric reductive amination of α-tetralone derivatives and indanone proceeds with >95% de. Lower diastereomeric excesses are observed for benzosuberone (16.7% de) and acetophenone (27.3% de). rac-21 gave (1′S,8′S,1(R)-25a (38% yield) and (1′R,8′S,1(R)-25b (44.5% yield) with greater than 52 and 78% de, respectively. Cleavage of the amino auxiliary of (1′S,8′S,1(R)-25a and of (1′R,8′S,1(R)-25b with lead(IV) tetraacetate and hydrolysis of the hydantoin ring yields the unprotected analogs of 4 and 5 . The latter are transformed into the selectively protected target molecules 4 and 5 through standard protection procedures. The overall yield of the 17- and 18-step synthesis starting from 13 was 0.3% yield for each constrained lysine derivative.

Building organic assemblies with 2-pyridone and dicarboxylic acids: relating molecular conformation and synthon stability to crystal structure

Abstract The syntheses and crystal structures of five cocrystals; 2-pyridone oxalic acid (2/1), 2-pyridone succinic acid (2/1), 2-pyridone adipic acid (2/1) dihydrate, 2-pyridone suberic acid (2/1), and 2-pyridone sebacic acid (2/1), are reported. The competition between two similar self-complementary hydrogen-bonded synthons (carboxylic acid and 2-pyridone) are examined systematically in this series of cocrystals. In each case, the crystal structure contains planar dimers of 2-pyridone which are bridged by a dicarboxylic acid via a combination of C–H ⋯ O and O–H ⋯ O hydrogen bonds to generate infinite 1-D ribbons. The orientation of these ribbons is determined by changes in molecular shape and conformational flexibility of the dicarboxylic acid.

Deliberate combination of coordination polymers andhydrogen bonds in a supramolecular design strategy for inorganic/organichybrid networks

Two crystal structures containing infinite CuI chains connected into 2-D layers by non-covalent interactions demonstrate how coordinate covalent bonds and hydrogen bonds can be combined in the design of new inorganic/organic hybrid materials.

Pitfalls in the supramolecular assembly of silver(I) coordination compounds

Abstract The syntheses and crystal structures of (6-methylnicotinic acid) (6- methylnicotinato)silver(I), di (6-methylnicotinic acid) silver(I) nitrate, (2-chloro-6-methylnicotinato) silver(I), di (2-chloro-6-methylnicotinic acid) silver(I) nitrate, and (2-methylni-cotinic acid) (2-methylnicotinato) silver(I) are described. These coordination complexes were synthesized under the same conditions and with very similar ligands but their resulting structures are quite different, in part due to the degree of protonation of the nicotinic acid ligand(s). The structures vary from coordination polymers to hydrogen-bonded coordination dimers, to linear structures linked by anion-carboxylic acid hydrogen bonds. This study illustrates some of the difficulties involved in predicting hydrogen-bonded networks in transition-metal systems which contain carboxylic acid moieties and coordinatively unsaturated metal ions.

Assembly of 2-D inorganic/organic lamellar structures through a combination of copper(I) coordination polymers and self-complementary hydrogen bonds

A strategy for the deliberate assembly of lamellar inorganic/organic hybrid materials based on a combination of 1-D coordination polymers and intermolecular hydrogen bonds has been explored. Copper(I) halide coordination polymers provide infinite linear building blocks that are linked into 2-D layers by attaching a pyridine-based ligand to each metal ion. The ligand, which carries a self-complementary hydrogen-bond moiety, provides a selective non-covalent tool for connecting neighboring coordination polymers into a 2-D network. The strategy is illustrated by the crystal structures of [CuCl(6-Me-3-HO2CC5H3N)]∞ and [CuI(6-Me-3-HO2CC5H3N)]∞, both of which display the desired lamellar motifs.