Combine chicken, tomatoes, broth, onion, bell pepper, garlic, Italian seasoning, pepper, salt, crushed red pepper and bay leaf in a 4-quart slow cooker. Cover and cook on High until the chicken is tender and an instant-read thermometer inserted into the thickest part of the chicken registers 165 degrees F, about 3 hours. Remove and discard the bay leaf. Transfer the chicken to a plate; let rest for 10 minutes.