The directed synthesis of two noncentrosymmetric sulfated molybdates has been achieved through the use of chiral organic amines. Reaction gels containing either (R)-2-methylpiperazine or (S)-2-methylpiperazine, MoO 3 , H 2 SO 4 , and H 2 O were subjected to mild hydrothermal conditions, resulting in the growth of single crystals of [(R)-C 5 H 14 N 2 ][(MoO 3 ) 3 (SO 4 )]‚H 2 O and [(S)-C 5 H 14 N 2 ][(MoO 3 ) 3 (SO 4 )]‚H 2 O. These materials crystallize in the noncentroysmmetric space group P2 1 2 1 2 1 (No. 19), which exhibits the enantiomorphic crystal class 222 (D 2 ). The second harmonic generation activities were measured on sieved powders.

Lemons (Citrus limon) are a desirable citrus fruit grown and used globally in a wide range of applications. The main constituents of this sour-tasting fruit have been well quantitated and characterized. However, additional research is still necessary to better understand the trace volatile compounds that may contribute to the overall aroma of the fruit. In this study, Lisbon lemons (C. limon L. Burm. f. cv. Lisbon) were purchased from a grove in California, USA, and extracted by liquid-liquid extraction. Fractionation and multidimensional gas chromatography-mass spectrometry were utilized to separate, focus, and enhance unidentified compounds. In addition, these methods were employed to more accurately assign flavor dilution factors by aroma extract dilution analysis. Numerous compounds were identified for the first time in lemons, including a series of branched aliphatic aldehydes and several novel sulfur-containing structures. Rarely reported in citrus peels, sulfur compounds are known to contribute significantly to the aroma profile of the fruit and were found to be aroma-active in this particular study on lemons. This paper discusses the identification, synthesis, and organoleptic properties of these novel volatile sulfur compounds.

Global production and demand for tropical fruits continues to grow each year as consumers are enticed by the exotic flavors and potential health benefits that these fruits possess. Volatile sulfur compounds (VSCs) are often responsible for the juicy, fresh aroma of tropical fruits. This poses a challenge for analytical chemists to identify these compounds as most often VSCs are found at low concentrations in most tropical fruits. The aim of this review is to discuss the extraction methods, enrichment techniques, and instrumentation utilized to identify and quantify VSCs in natural products. This will be followed by a discussion of the VSCs reported in tropical and subtropical fruits, with particular attention to the odor and taste attributes of each compound. Finally, the biogenesis and enzymatic formation of specific VSCs in tropical fruits will be highlighted along with the contribution each possesses to the aroma of their respective fruit.