unity 2d edition lookAt

    void LookAt2D(Transform target)
    {
        Vector3 dir = target.position - transform.position;
        float angle = Mathf.Atan2(dir.y, dir.x) * Mathf.Rad2Deg;
        transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);
    }

 Axis pointing in the direction X