F♯ over C (major triad over major triad a tritone apart).
C           E        G        A♯       C♯             F♯    
1           3        5        ♭7       ♭9             ♯11         

Parent scales are B♭ diminished (no 4 or 7) or C♯ diminished (no ♭9 or ♯5) or E diminished (no 4 or 7) or G diminished (no ♭9 or ♯5).
C  C♯       E     F♯ G        A♯
1  ♭2       3     ♯4 5        ♭7

Related chords (reverse diminished).
| A13♯9 (no 1 or ♯4) | C7♭9♯11 (no ♯9 or 6) | E♭13♯9 (no 1 or ♯4) | F♯7♭9♯11 (no ♯9 or 6) |