Donald Ayler was the younger brother of Albert Ayler, one of the most charismatic musicians in jazz. If it was his fate to be perpetually in the shadow of the music’s last great innovator, he made his contribution through jagged and unsettling trumpet work, heard on their recordings for Impulse and the radical ESP label, and with a statement that is a stepping stone to appreciating free jazz. A trumpeter known for his full, piercing tone, he performed with John Coltrane at Lincoln Center