Screening, manufacturing, photoluminescence, and molecular recognition of co-crystals: cytosine with dicarboxylic acids

Tu Lee, Pu Yun Wang

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

A workflow for screening and manufacturing co-crystals was used to produce 4:1 co-crystal of cytosine-oxalic acid dihydrate, 2:1 co-crystal of cytosine-malonic acid, and 2:1 co-crystal of cytosine-succinic acid with melting points of 270.2, 219.2, and 249.5 °C, and Kspvalues of 8.21 X 10-12m5,4.90 x 10-5 m3, and 3.11 X 10-6 m3 in water at 25 °C, respectively. 4:1 co-crystal of cytosine-oxalic acid dihydrate crystallized in the P2 1/c space group. Both 2:1 co-crystal of cytosine-malonic acid and 2:1 co-crystal of cytosine-succinic acid crystallized in the P1̄ space group. Co-crystals of cytosine with dicarboxylic acids all possessed a self-assembled cyclic pattern of R22(12) forming by a pair of N-H- ⋯ O hydrogen bonds within a dimeric motif of cytosine. The self-recognition pairing of cytosine here resembled the standard hydrogen bonding pattern in the Watson-Crick complementary base pairing of guanine and cytosine but without the middle N-H- ⋯N interaction. Both photoluminescence (PL) emission intensity and the solubility of co-crystals at a given temperature followed the same descending order of 2:1 co-crystal of cytosine-malonic acid > 2:1 co-crystal of cytosine-succinic acid > 4:1 co-crystal of cytosine-oxalic acid dihydrate. The weakening of the hydrogen bonding strength of 2:1 co-crystal of cytosine-malonic acid due to the angling of the interlayers might explain its lowest melting point of 219.2 °C, its highest solubility and its highest PL emission intensity.

Original languageEnglish
Pages (from-to)1435-1442
Number of pages8
JournalCrystal Growth and Design
Volume10
Issue number3
DOIs
StatePublished - 3 Mar 2010

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