Ternary co-crystals

Figure 8.45 Ternary co-crystal of the ditopic supramolecular coupling reagent 8.41 with two benzoic acid derivatives. The stronger 3,5-dinitrobenzoic acid interacts with the stronger imidazole base while the second best acid, 4-nitrobenzoic acid interacts with the second best pyridyl base.

Co-crystal 6, 4-(N,N-dimethyl)aminobenzoic acid isonicotinamide 3,5-dinitro-benzoic acid (1 1 1), is also a ternary co-crystal with the intended three-component supermolecule. The acid-pyridine nitrogen interaction persists, and the weaker acid (pKa=6.5) forms a heteromeric motif with the amide moiety, Fig. 2.5.3. 

Dinitrobenzoic acid isonicotinamide 4-hydroxy-3-methoxycinnamic acid 7, is also a 1 1 1 ternary co-crystal with the same primary supramolecular connectivity... 

Phosphine oxide-based olefination reactions continue to be widely used in synthesis, for example, in those leading to vitamin D3 and its derivatives. An alternative method for the conversion of diastereomerically pure menthyl phosphinates to optically active phosphine oxides has been reported. Structural studies on a variety of phosphine oxide binary and ternary co-crystallization compounds have been carried out and the first complex involving the binary PO ligand has been prepared. 

Figure 5.4 Hierarchic hydrogen bonding between acid, pyridine and amide groups in ternary co-crystals strongest acid- -pyridine and next best acid- - -amide heterosyn-thons. (a) 4-Dimetbylaminobenzoic acid isonicotinamide 3,5-dinitrobenzoic acid and (b) 3,4-dimethoxycinnamic acid isonicotinamide 3,5-dinitrobenzoic acid...

Figure 7.8 Hydrogen bonding patterns in the ternary co-crystals of iso-nicotinamide (3) with (a) 3,5-dinitrobenzoic acid and 4-(dimethylamino)benzoic acid and (b) 3,5-dinitrobenzoic acid and 4-hydroxy-3-methoxybenzoic acid...

Figure 2.10 Hydrogen-bonded units within the ternary co-crystals (a) 3,5-dinitro-benzoic acid isonicotinamide 3-methylbenzoic acid (1 1 1), (b) 3,5-dinitrobenzoic acid isonicotinamide 4-(V,iV-dimethylamino)benzoic acid (1 1 1), and (c) 3,5-dinitrobenzoic acid isonicotinamide 4-hydroxy-3-methoxycinnamic acid (1 1 1), incorporating isonicotinamide and carboxylic acids with different hydrogen-bond donor strengths. ...

Figure 2.11 Hydrogen-bonded unit within the ternary co-crystal 3,5-dinitrobenzoic acid 4-nitrobenzoic acid 1 -((3-pyridyl)methyl)benzimidazole (1 1 1), containing a multi-functional base combined with two different carboxylic acids. ...

Figure 2.12 Hydrogen-bonded imit within the hydrated ternary co-crystal cyclohexane-1, 3,5-tricarboxylic acid 4,4 -bipyridine 4,4 -bipyridine-iV,iV -dioxide (2 1 1) dihydrate. In the crystallographic model, proton transfer is considered to occur for one O-H -N hydrogen bond.

Table 3 pATj values of acids used in the s mthesis of ternary co-crystals with wo-nicotinamide... 

If the best donor binds to the best acceptor and the second best donor to the second best acceptor, then this strategy should yield ternary co-crystals. The experimental setup used is shown in Table 3. 

The products of these reactions were again characterized by single-crystal X-ray diffraction, and, remarkably, ternary co-crystals with the postulated connectivity were obtained in all three cases. The stronger acid, 3,5-dinitro benzoic acid, formed a hydrogen bond with the pyridyl group, the best acceptor. The weaker acid formed an acid-amide dimer with the amide group, the second best acceptor site (Fig. 7). 

Scheme 15 Postulated outcome for a ternary co-crystal based on MEP surface calculations...

Fig. 10 The two most important hydrogen-bond interactions in a ternary co-crystal of A-hydro-xybenzimidoyl cyanide, pentamethylbenzoic acid, and a ditopic hydrogen-bond acceptor...

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