Isotope 217, one of Rob Mazurek’s numerous Chicago jazz side projects, finds itself in a precarious position somewhere between post-rock and jazz. Isotope grew out of weekly jam sessions around the Chicago area and are put on record for the first time. Recruiting members of Tortoise (Dan Bitney, John Herndon, and Jeff Parker) for this effort, there is a pronounced lo-fi vibe, which is counteracted by Mazurek’s jazz ambition. The end result is an album that is neither straight-ahead jazz or space-rock, but a quirky, funk-flavored, astute musical venture. Tracks like “Kryptonite Smokes the Red Line” and “La Jeteé” explore mellow spaces and employ the uses of varied instrumentation including cello and other strings. “Audio Boxing” and “Beneath the Undertow” rely on catchy horn arrangements and precise construction, while providing a counterpoint to the subdued nature of the other tracks. The Unstable Molecule will satisfy anyone who has a taste for out of the ordinary jazz, and an inclination toward funk would not hurt either. It provides a consistent listen, but must be understood as a bridge between two genres. It is a serious effort to assimilate a post-rock sound with contemporary jazz, and it succeeds well. – Marc Gilman